2001 Tahoe Blinking Check Engine Light?

[Justin509]

2001 Tahoe
205k
5.3
4wd

I just had a trip to Oregon about 1k miles round trip. Just as I got back in town I had my cruise control on and was doing about 65mph and started to go up a hill and I noticed when it went from 1500rpm to 3000pm it was pulsing like it wanted to go faster but it wouldn't like a miss fire. Then I noticed the check engine light blinking. So I turned cruise control off and brought it down to 65mph and about 1800rpm and the blinking check engine light went off.. Then I wot to see if it went away and it did the same thing. Check engine light started blinking... I found a little info saying that when the check engine light blinks that means its a miss fire. So I took it to auto zone and had no codes.. So I then pulled the maf and cleaned it. Still no change..So then I pulled the plugs which look original and changed them along with new wires. Still no change! So whats my next step? Coil packs?? Is their a way to test them? Anyone have this problem?

[Thumper8302]

as far as the coil pack testing goes u can take them up to autozone and they will check them for free.... kinda funny how no codes were stored in memory. kinda makes me wonder if ur tranny is starting to have issues.. hope u find the problem man

[fire730]

Usually a flashing CEL means that catalytic converter damage is likely to occur. Usually a misfire causing raw fuel to be dumped into the converter. As far as pinpointing which one it is hard to find out which one until the computer tells you which cylinder is causing it.

[sumo]

Usually a flashing CEL means that catalytic converter damage is likely to occur. Usually a misfire causing raw fuel to be dumped into the converter. As far as pinpointing which one it is hard to find out which one until the computer tells you which cylinder is causing it.

exactly. But its not Likely, its Means it is.

[SunlitComet]

A flashing CEL is a active misfire and a scanner with enhanced gm diagnostics can tell you the misfire history of each cylinder to pinpoint which cylinder(s) is given you the problems. Look for stored codes as well not just active one. It should be address ASAP as it could not be just a malfunctioning injector that is putting out no fuel but also could be a no spark issue where raw fuel gets dumped into the converter causing it to overheat and melt the substrate but also washing down the cylinder wall.

---------- Post added at 09:55 PM ---------- Previous post was at 09:54 PM ----------

BTW Justin, :welcome:

[Justin509]

So for the last day I have been trying to figure out what the problem is. I pulled the tb off and cleaned it. It looks like it has never been touched! But still no help. Also is their a way to test the maf sensor? I'm also thinking that it could be and injector but I am not sure which one since I have no codes. I'm picking up a scanner today and will see if any have been stored. I'm hoping that one is in their and will tell me whats going on.
Before
http://i223.photobucket.com/albums/dd47/sparkplug1288/347d5ee2.jpg
http://i223.photobucket.com/albums/dd47/sparkplug1288/ee0aceff.jpg

After
http://i223.photobucket.com/albums/dd47/sparkplug1288/51eab880.jpg
http://i223.photobucket.com/albums/dd47/sparkplug1288/fed310d5.jpg
http://i223.photobucket.com/albums/dd47/sparkplug1288/3a739042.jpg
http://i223.photobucket.com/albums/dd47/sparkplug1288/625eb06f.jpg

---------- Post added at 10:20 AM ---------- Previous post was at 10:15 AM ----------

Also here is a shot of the old plugs.
http://i223.photobucket.com/albums/dd47/sparkplug1288/6ff7d029.jpg

[fire730]

Usually the MAF will set a code.

You can eat off your TB now. But a dirty TB wouldn't cause a stumble anywhere over idle speed.

Those plugs were definitely wiped out.

What did you replace them with?

[SunlitComet]

1. yeah that is 205k miles on that tb.
2. Those plugs are beyond gone. Are they not supposed to be platinum type?
3. the scanner will either read back the output voltage or Air poundage that the Maf sees.

[fire730]

I thought that all the 5.3s used platinum plugs. He definitely wore off the platinum on those babies.

[SunlitComet]

those do not look like platinum's at all. The look to straight solid core to me.

[fire730]

If I remember correctly the Delco plugs have a spot of platinum on the ground electrode that you can see as the little white dot on the plug on the bottom.

[SunlitComet]

there iridium for 2001 look like this:

http://www.acdelco.com/images/bn_iridium_plug.jpg

---------- Post added at 09:07 PM ---------- Previous post was at 09:06 PM ----------

BTW, why is there a hole in the throttle plate?

[fire730]

They are worn out but I really can't see those being original plugs. 200k miles. I just cant see that happening. Not impossible but I cant see it happening.

[SunlitComet]

I think someone just replaced them with the wrong ones.

[Thumper8302]

damn.. that throttle body was nasty as hell... im pushin 240xxx on mine and ive only cleaned mine with a tooth brush and a rag with it still on the motor.... kinda been leery on yankin it and actually CLEANIN it... was it a pain gettin the butterfly out? and how much of a pain was it installin it back to the manifold?

[Justin509]

I put autolite xp iridium plugs back in. As far as the plugs being factory that's what it's looking like. They are acdelco ngk pztr5a and are long gone! Lol... As far as cleaning the tb while it was still bolted up I didnt want dirt and gunk travel down stream to my injectors. After I cleaned that I pulled both fuel rails and made a little home made injector cleaning setup. And I'm on my last injector... Ill put it all back together and see how it runs. If it still running bad then I guess it's gonna be one of the coils.

[Justin509]

This is the home made setup I made to clean the injectors.. Dont laugh lol it works..
http://i223.photobucket.com/albums/dd47/sparkplug1288/7b2a8164.jpg

---------- Post added at 10:28 PM ---------- Previous post was at 10:24 PM ----------

O and after all the injectors were cleaned and put back in it still is missing! so I will be getting it on a scanner in the morning to see what is exactly going on.

[Diggerdan11]

The same exact thing just happend to me this last weekend. The week before the CEL came on on the Tahoe so I went to o'reilly's and borroed there Scanner and it showed the P0420 and P0430 codes which are Catalyst efficency belwo threshold. I figured it would not be that big of a deal to drive it for a couple weeks till i could get it figured out. Well i attempted to accelerate up a hill and the truck lost power the RPMs started to bounce and the CEL started flashing. I took it right back to O'reilly's and it showed a code saying there was a missfire. I have read that a clogged Cat could definetly cause a problem within the Cylinders and a missfire because the gas has not where to escape.

Its strange that the scanner did not show a code. I went to Autozone to use there scanner and it would not connect to my tahoe for some reason. you may want to go to another auto place and seem if they have a better scanner


BTW what part of Oregon did you go to?

[SunlitComet]

The same exact thing just happend to me this last weekend. The week before the CEL came on on the Tahoe so I went to o'reilly's and borroed there Scanner and it showed the P0420 and P0430 codes which are Catalyst efficency belwo threshold. I figured it would not be that big of a deal to drive it for a couple weeks till i could get it figured out. Well i attempted to accelerate up a hill and the truck lost power the RPMs started to bounce and the CEL started flashing. I took it right back to O'reilly's and it showed a code saying there was a missfire. I have read that a clogged Cat could definetly cause a problem within the Cylinders and a missfire because the gas has not where to escape.




Diggerdan you definitely need new converters.

[Diggerdan11]

Diggerdan you definitely need new converters.

yeah i know, bad.

Im going to get them in a few more weeks. Im getting maried in a couple weeks so im going to try to wait until after that to do it, since im going to replace them myself. For now my Fiance is only allowed to drive it to and from work which is about a mile and a half each way.

[Justin509]

I'll see if I can bring it to a muffler shop and see what they say.. I ended up going to Portland zoo and then canby for the weekend.

[Diggerdan11]

I'll see if I can bring it to a muffler shop and see what they say.. I ended up going to Portland zoo and then canby for the weekend.

Sweet I have always liked the Portland zoo. Haven't been there in a while though

[Justin509]

Still having the same problem

[SunlitComet]

What was that hole in your throttle butterfly? And have you had any luck with getting a cylinder misfire history?

[Justin509]

Im not sure what the hole is..And still no cylinder misfire history! This is gonna drive me crazy.. And is sucking gas fast! Its worse now.... When I hold it steady a 3krpm it bucks/pulses not sure how to say it. Like brum........brum.......brum.....brum holding it at 3k steady lol

[SunlitComet]

Unless someone proves me wrong that hole should not be there. And I think it needs to be addressed. Did you make it to an exhaust shop for a check-out or no?

[Justin509]

Not yet... Im gonna try and get it in tomorrow

[Justin509]

Ok so I have a p0446 code. Could this cause the Tahoe to run like this? I have no power what so ever. 3/4 throttle and just barley goes. Wot and it shifts down and will rev high but no power.

[SunlitComet]

here is a whole tech article on it:

Vehicle (http://www.alldatadiy.com/alldata/AFI%7EV27036441%7EC33210%7ER0%7EOD%7EN/0/70910848/78153753/78154197/78154199/34853741) » Powertrain Management (http://www.alldatadiy.com/alldata/AFI%7EV27036441%7EC33210%7ER0%7EOD%7EN/0/70910848/78153753/78154197/78154199/34853741/34857029) » Computers and Control Systems (http://www.alldatadiy.com/alldata/AFI%7EV27036441%7EC33210%7ER0%7EOD%7EN/0/70910848/78153753/78154197/78154199/34853741/34857029/34857030) » Testing and Inspection (http://www.alldatadiy.com/alldata/AFI%7EV27036441%7EC33210%7ER0%7EOD%7EN/0/70910848/78153753/78154197/78154199/34853741/34857029/34857030/34857663) » Diagnostic Trouble Code Tests and Associated Procedures (http://www.alldatadiy.com/alldata/AFI%7EV27036441%7EC33210%7ER0%7EOD%7EN/0/70910848/78153753/78154197/78154199/34853741/34857029/34857030/34857663/122915129) » P Code Charts (http://www.alldatadiy.com/alldata/AFI%7EV27036441%7EC33210%7ER0%7EOD%7EN/0/70910848/78153753/78154197/78154199/34853741/34857029/34857030/34857663/122915129/105258193) » P0446 (http://www.alldatadiy.com/alldata/AFI%7EV27036441%7EC33210%7ER0%7EOD%7EN/0/70910848/78153753/78154197/78154199/34853741/34857029/34857030/34857663/122915129/105258193/105298944) http://www.alldatadiy.com/includes/img/content/icon_note_blank.gif Notes P0446
http://www.alldatadiy.com/alldata/AFI%7EV27036441%7EC33210%7ER0%7EOB0%7EP4R0H%7EN/0/70910848/78153753/78154197/78154199/34853741/34857029/34857030/34857663/122915129/105258193/105298944/167361288/167361289


http://www.alldatadiy.com/alldata/AFI%7EV27036441%7EC33210%7ER0%7EOB0%7EP4R0H%7EN/0/70910848/78153753/78154197/78154199/34853741/34857029/34857030/34857663/122915129/105258193/105298944/167361288/78582444


http://www.alldatadiy.com/alldata/AFI%7EV27036441%7EC33210%7ER0%7EOB0%7EP4R0H%7EN/0/70910848/78153753/78154197/78154199/34853741/34857029/34857030/34857663/122915129/105258193/105298944/167361288/167361290


http://www.alldatadiy.com/alldata/AFI%7EV27036441%7EC33210%7ER0%7EOB0%7EP4R0H%7EN/0/70910848/78153753/78154197/78154199/34853741/34857029/34857030/34857663/122915129/105258193/105298944/167361288/78582447



Circuit Description
The VCM (http://www.alldatadiy.com/alldata/AFI%7EV27036441%7EC33210%7ER0%7EOD%7EN/0/70910848/78153753/78154197/78154199/34853741/34857029/34857030/101367125) monitors the performance of the EVAP system by applying a predetermined level of vacuum to the EVAP system and monitors the vacuum decay rate. The VCM sets this DTC if the vacuum decay rate is greater than a predetermined value. The VCM monitors the amount of vacuum and the amount of pressure in the EVAP system by monitoring the Fuel Tank Pressure sensor (http://www.alldatadiy.com/alldata/AFI%7EV27036441%7EC33210%7ER0%7EOD%7EN/0/70910848/78153753/78154197/78154199/34853741/34857029/34857030/101367736). For this DTC the VCM turns ON both the EVAP (http://www.alldatadiy.com/alldata/AFI%7EV27036441%7EC33210%7ER0%7EOD%7EN/0/70910848/78153753/78154197/78154199/34853741/34857029/34857699/34872077) Purge Valve and the EVAP Vent Valve when the Conditions for Running the DTC are met. This applies an engine vacuum to a closed EVAP system. The VCM turns OFF both the EVAP Purge Valve and the EVAP Vent Valve when the system reaches a correct amount of vacuum. The EVAP system should quickly RELEASE the vacuum in the EVAP system with the EVAP Purge Valve OFF and the EVAP Vent Valve OFF (open). This test indicates a blocked or restricted EVAP Vent Valve or path if the EVAP system fails to release the vacuum quickly enough.

Conditions for Running the DTC


No active MAP sensor DTCs
No active TP sensor DTCs
No active VS sensor DTCs
No active O2 sensor DTCs
No active ECT sensor DTCs
No active IAT sensor DTCs
DTC P0125 not active
The fuel level is greater that 12.5% but less than 87%
The system voltage is between 10 and 17 volts
The ECT is between 4°C and 30°C (39°F to 86°F)
The IAT (http://www.alldatadiy.com/alldata/AFI%7EV27036441%7EC33210%7ER0%7EOD%7EN/0/70910848/78153753/78154197/78154199/34853741/34857029/34857030/34857031) is between 4°C and 30°C (39°F to 86°F)
The cold start temperature difference (ECT minus IAT (http://www.alldatadiy.com/alldata/AFI%7EV27036441%7EC33210%7ER0%7EOD%7EN/0/70910848/78153753/78154197/78154199/34853741/34857029/34857030/34857031)) is less than 1.5°C when the IAT is greater than the ECT or 8°C when the ECT is greater than the IAT
The BARO is greater than 72 kPa
The change in fuel tank (http://www.alldatadiy.com/alldata/AFI%7EV27036441%7EC33210%7ER0%7EOD%7EN/0/70910848/78153753/78154197/78154199/34853741/34857029/34858641/34859372) vacuum is less than 0.6 in. of H2O, or the change in fuel level is less than 8%
The fuel tank (http://www.alldatadiy.com/alldata/AFI%7EV27036441%7EC33210%7ER0%7EOD%7EN/0/70910848/78153753/78154197/78154199/34853741/34857029/34858641/34859372) vacuum level remains above a calibrated value for a specified number of seconds

Conditions for Setting the DTC
The VCM (http://www.alldatadiy.com/alldata/AFI%7EV27036441%7EC33210%7ER0%7EOD%7EN/0/70910848/78153753/78154197/78154199/34853741/34857029/34857030/101367125) fails to detect a drop in the EVAP system vacuum over a calibrated number of seconds with the vent solenoid (http://www.alldatadiy.com/alldata/AFI%7EV27036441%7EC33210%7ER0%7EOD%7EN/0/70910848/78153753/78154197/78154199/34853741/34857029/56218937/80820791) open.

Action Taken When the DTC Sets



The VCM (http://www.alldatadiy.com/alldata/AFI%7EV27036441%7EC33210%7ER0%7EOD%7EN/0/70910848/78153753/78154197/78154199/34853741/34857029/34857030/101367125) illuminates the MIL (http://www.alldatadiy.com/alldata/AFI%7EV27036441%7EC33210%7ER0%7EOD%7EN/0/70910848/78153753/78154197/78154199/34853741/34857029/34857030/34857480) during the first key cycle in which the DTC sets.
The VCM (http://www.alldatadiy.com/alldata/AFI%7EV27036441%7EC33210%7ER0%7EOD%7EN/0/70910848/78153753/78154197/78154199/34853741/34857029/34857030/101367125) stores the conditions that were present when the DTC sets as a Freeze Frame and Fail Records data.

Conditions for Clearing the MIL (http://www.alldatadiy.com/alldata/AFI%7EV27036441%7EC33210%7ER0%7EOD%7EN/0/70910848/78153753/78154197/78154199/34853741/34857029/34857030/34857480)/DTC



The Control Module (http://www.alldatadiy.com/alldata/AFI%7EV27036441%7EC33210%7ER0%7EOD%7EN/0/70910848/78153753/78154197/78154199/34853741/34857029/56218937/97115128) turns OFF the MIL after 3 consecutive drive trips when the test has Run and Passed.
A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles (coolant temperature has risen 22°C (40°F) from the start-up coolant temperature and the Engine Coolant Temperature is more than 70°C (158°F) during the same ignition cycle).
Use the scan tool Clear Information function.

[SunlitComet]

Diagnostic Aids

Important: An accurate indication of fuel level is required for the VCM (http://www.alldatadiy.com/alldata/AFI%7EV27036441%7EC33210%7ER0%7EOD%7EN/0/70910848/78153753/78154197/78154199/34853741/34857029/34857030/101367125) to properly Pass or Fail this DTC. Always diagnose fuel level sensor (http://www.alldatadiy.com/alldata/AFI%7EV27036441%7EC33210%7ER0%7EOD%7EN/0/70910848/78153753/78154197/78154199/34853741/34857029/34857030/101367480) DTCs before performing this DTCs diagnostic table. Always check for fuel level sensor DTCs stored in History.

Check for the following conditions:



A loose, missing, damaged, incorrect or improperly installed fuel cap
Missing or damaged O-rings at EVAP canister (http://www.alldatadiy.com/alldata/AFI%7EV27036441%7EC33210%7ER0%7EOD%7EN/0/70910848/78153753/78154197/78154199/34853741/34857029/34857699/34872077) fuel vapor and purge line fittings
A cracked or punctured EVAP canister (http://www.alldatadiy.com/alldata/AFI%7EV27036441%7EC33210%7ER0%7EOD%7EN/0/70910848/78153753/78154197/78154199/34853741/34857029/34857699/34872077)
Incorrectly routed or defective EVAP system vacuum and vapor lines
A damaged or disconnected EVAP (http://www.alldatadiy.com/alldata/AFI%7EV27036441%7EC33210%7ER0%7EOD%7EN/0/70910848/78153753/78154197/78154199/34853741/34857029/34857699/34872077) purge line, vent hose or fuel tank (http://www.alldatadiy.com/alldata/AFI%7EV27036441%7EC33210%7ER0%7EOD%7EN/0/70910848/78153753/78154197/78154199/34853741/34857029/34858641/34859372) vapor line
A stuck closed EVAP Vent Valve
A restricted or stuck closed fuel tank (http://www.alldatadiy.com/alldata/AFI%7EV27036441%7EC33210%7ER0%7EOD%7EN/0/70910848/78153753/78154197/78154199/34853741/34857029/34858641/34859372) rollover valve
A poor connection at the VCM (http://www.alldatadiy.com/alldata/AFI%7EV27036441%7EC33210%7ER0%7EOD%7EN/0/70910848/78153753/78154197/78154199/34853741/34857029/34857030/101367125): Inspect the harness connectors for the following conditions:
Backed out terminals
Improper mating
Broken locks
Improperly formed or damaged terminals
poor terminal to wire connection
A damaged harness: Inspect the wiring harness to the EVAP (http://www.alldatadiy.com/alldata/AFI%7EV27036441%7EC33210%7ER0%7EOD%7EN/0/70910848/78153753/78154197/78154199/34853741/34857029/34857699/34872077) vent solenoid (http://www.alldatadiy.com/alldata/AFI%7EV27036441%7EC33210%7ER0%7EOD%7EN/0/70910848/78153753/78154197/78154199/34853741/34857029/56218937/80820791), EVAP purge solenoid and the fuel tank pressure sensor (http://www.alldatadiy.com/alldata/AFI%7EV27036441%7EC33210%7ER0%7EOD%7EN/0/70910848/78153753/78154197/78154199/34853741/34857029/34857030/101367736) for an intermittent, open or short circuit
A kinked, pinched or plugged EVAP (http://www.alldatadiy.com/alldata/AFI%7EV27036441%7EC33210%7ER0%7EOD%7EN/0/70910848/78153753/78154197/78154199/34853741/34857029/34857699/34872077) purge, or fuel tank (http://www.alldatadiy.com/alldata/AFI%7EV27036441%7EC33210%7ER0%7EOD%7EN/0/70910848/78153753/78154197/78154199/34853741/34857029/34858641/34859372) vapor line. Verify that the lines are not restricted

Reviewing the Fail Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.

Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table.



If the vacuum stored in the EVAP system is quickly released then an intermittent system restriction or failure of the EVAP Vent Valve or the EVAP (http://www.alldatadiy.com/alldata/AFI%7EV27036441%7EC33210%7ER0%7EOD%7EN/0/70910848/78153753/78154197/78154199/34853741/34857029/34857699/34872077) Fuel Tank Pressure Sensor (http://www.alldatadiy.com/alldata/AFI%7EV27036441%7EC33210%7ER0%7EOD%7EN/0/70910848/78153753/78154197/78154199/34853741/34857029/34857030/101367736) may have occurred.
Checking the vapor canister and the EVAP Vent Valve for restriction.



An EVAP Pressure sensor that does not correctly respond to pressure (or vacuum) will cause this DTC to set. The EVAP Pressure Sensor monitors a range from 7.5 in. H2O of pressure to -17.5 in. H2O of pressure (vacuum). In order to test the EVAP Pressure sensor for pressure response SEAL the system with the scan tool and use the EVAP (http://www.alldatadiy.com/alldata/AFI%7EV27036441%7EC33210%7ER0%7EOD%7EN/0/70910848/78153753/78154197/78154199/34853741/34857029/34857699/34872077) pressure/purge diagnostic cart to apply pressure to the system. Compare the pressure gauge (in. H2O) on the diagnostic cart to the EVAP Pressure sensor reading on the scan tool.


---------- Post added at 03:09 PM ---------- Previous post was at 03:05 PM ----------

bullets number 1-2-1 for chart above are actually 4-5-9

---------- Post added at 03:14 PM ---------- Previous post was at 03:09 PM ----------

This generally is the warning for a loose gas cap.

[Justin509]

I got the cats checked and guess what?

[SunlitComet]

They were not there?

---------- Post added at 05:08 PM ---------- Previous post was at 04:52 PM ----------

Plugged?
Blown out?

Absolutely Fabulous!

[Justin509]

The passenger side is completly clogged! So im guessing that that is the reasone why its running like it is and sucking so much gas?
Can I just pull them and put stright pipe??

[SunlitComet]

That will fail a smog test piss your computer off and is generally illegal. Get your self a Direct bolt-on magnaflow hi-flow cats if. About $600.

http://www.allexhaust.com/magnaflowcatalyticconverter/images/L/45419.gif

---------- Post added at 05:33 PM ---------- Previous post was at 05:29 PM ----------

And should be 50 state compliant.

[Justin509]

Will this work?
http://www.theautopartsshop.com/Search/Default.aspx?Pat=chevrolet+tahoe+catalytic-converter&Key=auto+car-usa+parts&gpartnum=03CheTahoe%2FEA83166&utm_source=google&utm_medium=camp3&utm_content=Catalytic%20Converter&utm_campaign=chevrolet

[SunlitComet]

YES! direct bolt on 50 state legal as well. your o2 sensors just transfer over although I would recommend replacement pf them all if they are all original. If nothing else is wrong you would pass a smog with flying colors an get power back to normal if not a little better.

[Justin509]

So before I ordered the new cats I pulled the clogged one out just to make sure that was it and it runs great now! Amazing how that caused it to run so bad.. So now Im going to order the new cats. Im going to change both because I can see the other one going bad. Thanks for all the help....

[SunlitComet]

Actually when you order the direct bolt you don't have a choice you get the whole assembly I pictured above. And of course it is the smart thing to do.

Post some pics of the cats. Would like to see how bad they are. I am guessing there are burned shut from running a rich mixture down them.

---------- Post added at 08:45 PM ---------- Previous post was at 08:29 PM ----------

Also I would still recommend some one with the same engine chime in here. I could be wrong, but a open hole in the throttle plate just does not sound right and maybe along with old o2 sensors maybe be causing this mess for you I mean the TB, WOW.

It is like someone drilled a hole to get the engine to run faster for a high electric load or something.

[Spikeymikey]

So my 03 Tahoe started the flashing CEL for the first time anytime I went above 65 on the freeway. Guess I should start with going to autozone to test it?

[SunlitComet]

:welcome:

You are getting a active misfire the scanner will help determine where and why.

[NJTaho]

Actually when you order the direct bolt you don't have a choice you get the whole assembly I pictured above. And of course it is the smart thing to do.

Post some pics of the cats. Would like to see how bad they are. I am guessing there are burned shut from running a rich mixture down them.

---------- Post added at 08:45 PM ---------- Previous post was at 08:29 PM ----------

Also I would still recommend some one with the same engine chime in here. I could be wrong, but a open hole in the throttle plate just does not sound right and maybe along with old o2 sensors maybe be causing this mess for you I mean the TB, WOW.

It is like someone drilled a hole to get the engine to run faster for a high electric load or something.

I'm pretty sure the hole you are talking about is normal. I've seen it on just about every car i've owned. 1996 Maxima, 1996 Explorer, 2000 Explorer, and my 2001 Tahoe, all had similar holes. Also I have seen completely solid blades. I have read that people who are tuning their vehicles themselves will drill a hole to help with Idle. (I'm not suggesting to do this at all)

I think it just depends on your vehicle.

[WildBill]

I cant see the invisible throttle body. Any pictures of the rest of the system?

[Spikeymikey]

I took mine to Autozone today and it didn't pick up on any codes. Do I have to hook one of these diagnostic machines while I am driving on the highway above 65 mph to get it to catch CEL? Besides cat replacement. Could it be something else like EGR valve? It also seems like my oil pressure runs pretty high. It idles at 40, but when I cruise at 2000 rpm it goes up to 60, and hits pretty close to 80 when I gun it. I just put in royal purple 5w30, k&n oil filter, & replaced the oil pressure sensor this weekend. No change to symptoms above after the maintenance.

[SunlitComet]

look at misfire history. Would not worry about oil pressure right now.

[tahoe7689]

I have an 03 tahoe with a 5.3L, and I had this same issue happen to me. After the blinking CEL, my car drove like yours, wouldnt shift and shook, basically sounded and felt like it would blow up haha. I had the cats replaced, BUT you need to make sure you fix the original problem that caused your cats to go bad, otherwise youll just blow your new cats all over again. From what you have said you have done, you may have caught the issue, but like I said make sure you have done everything you can because youll just have to replace the cats when they go bad again. A vehicle that functions normally should never have to replace the cats, from what I'm told, so the cats going bad means you have an issue with something else. (and yes the hole in the tb is normal for our model tahoes 00-06)

[Tahoe03mm]

I have a 6.0 lq4 and I too am having this problem, checked codes and only P0300. I have a dead cylinder #3 basically. I have a gauge that monitors missfires it says 3 but I never get a dtc for that cylinder. there's a huge history of things i've went through including.

swapping coil packs around - no difference
there is no cats - so they can't be plugged
MAF was having issues and previously had a code for it- replaced it
did compression check and it seemed ok
plug looked pretty fouled up
installed plug on end of wire and grounded - saw decent spark
checked fuel pressure at idle and while under load - between 50-60
fuel filter has been replaced
plugs and plugwires have been replaced
throttle body has been cleaned
i know there is no intake leaks because i just put the manifold back on


i'm thinking possible the injector but plug is pretty black to have no fuel unless the injector has some irregular spray pattern or something.

any ideas?

is there a way to test the coil wiring to the coil at the plug and verify the values it should be receiving from the computer?

[AZ-Yukon]

How did the intake manifold gaskets look when you had the intake off? I had similar behavior (rough idle vs. loss of power), and chased it around for some time. Finally replaced the intake manifold gaskets... problem solved. They didn't look that bad but were obviously leaking, especially when the engine was cold in the winter (Phoenix winter).