First post here, so hello all. I am a German car guy who just picked up a 98 tahoe cheap for a DD and don't know much about it/ american cars for that matter.
Truck:98 tahoe LT 350 vortec 5.7 completly stock. 105k
Issue: When the truck is WARM here ar the symptoms.
When in P or N it idels smooth as silk. Quiet, nice
But, when it is in gear and I am on the brake at a red light, it shudders/misses/binds inconsistantly. with anywhere from 10-60 seconds between shudders/misses/binding. Also, I will be at a light, and all will be good for anywhere from 10-60seconds, then you can feel the car shudder/miss/binding once maybe twice, maybe 8 times, or sometimes not at all. It is pretty suttle, but noticable. It doesnt start doing this until the engine is warm. But it will start softly at first, but as the car gets warmer starts. It does not do this everytime I stop either. I might go 1-5 red lights with out it. then it will do it again, though I have noticed that as the weather warms up it get worse. Sometimes it will do it once or twice at a red light, then not at the next red light. The point is that it is super inconsistant. When is starts to do it, i have tried to kick it in to N and that smooths it right ou. So it is load related. With that said it all started last week when i hadd 700LB's of fryer oil in the truck for a 20 mile trip in 90 degree heat.
Next symptom is when the light turns green and i come off the brake to the gas, it will slightly buck/miss/shudder/bind for the first 2-3 feet/seconds then smooth out fine. That is more consistant, meaning it happens ALMOST every time i set off, weather is was "missing" while i was at the red light or not. So in other words, i will be on the brake, truck is puurring like a kitten, then i go to set off, and it shudders/bucks/misses/binds. But even this does not happen every time, and does not happen when the truck is cold. but after that first "miss" it drive great...until...
The next symptom happen around 30-70mph, but cruising. lets say i am going 55mph and i give it a little gass to keep it steady. it will buck a bit, maybe 2-3 times. If i go more them about 1/4 throttle, it is fine, if i floor it it is fine. This is also inconsistant, and worse when the truck/weather is warm.
Last symptom is as inconsistant as the rest, and that is a slight lack of power. Meaning it will drive strong, and fine, then will be down on power a bit under all driving condidtions, then back to fine and so on. there is no common freguency the the power lose and it is minimal, but i do notice it.
None of these symptoms happen when the truck is cold. It drives very well actually. If i had to put the 4 symptoms in order of frequency, i would say that the taking off from a red light shudder/miss/ bind happen the most frequently, then the Shudder/miss/binding while at the red light, followed by the cruising shudder/miss/bind. All garnished with spratic light loss of power here and there.
So far i have done thes relating to this prob...
-plugs, wires, (both not ac delco but i didnt know about that until recently, and the truck ran fine for 2-3 months with those in).
-Cleaned EGR valve a bit, but it was a bit sticky when i pulled it off so i gave it a Little PB blaster which seemed to help it not stick while it was out of the car and cool, but when hot with exhaust who knows.
-fuel filter
-fuel pressure test, this one was interesting cuz at idel it is at 54psi and a WOT it is at 60psi. From what i understand those are acceptible numbers, but the spec is 60-66psi. and it is consistant. Meaning when the car acts up, the fuel pressure is not drop or raise at all. I also tested the fuel pressure 3 moths ago when i got it, and it was the same numbers.
-Trans filter.
I have done a ton of other thing to the truck (alternator, batt, all brakes all around, brake lines, fuel fillerneck, swaybar enlinks, water pump, radiator etc) none of which i think have anything to do with this issue.
Today i plan on cleaning the maf and throttle body. will let you all know if that helps.
But today I started to think it may be trans related. May torque converter? would the shaking/shuddering/miss while at the red light dismiss that though?
If the TB and MAF cleaning dont do anything, my next step is back to plugs wires with ACD brand, rotor button, and dist cap. I will also check the distributor for shaft play while i am there.
I have been reading online for days, and alot of people have a lot of the same symptoms as me, but no one i have seen yet has the Red Light shudder/miss/bind. Issue. thats whats killing me. Amy help would be apprecitated.
Truck:98 tahoe LT 350 vortec 5.7 completly stock. 105k
Issue: When the truck is WARM here ar the symptoms.
When in P or N it idels smooth as silk. Quiet, nice
But, when it is in gear and I am on the brake at a red light, it shudders/misses/binds inconsistantly. with anywhere from 10-60 seconds between shudders/misses/binding. Also, I will be at a light, and all will be good for anywhere from 10-60seconds, then you can feel the car shudder/miss/binding once maybe twice, maybe 8 times, or sometimes not at all. It is pretty suttle, but noticable. It doesnt start doing this until the engine is warm. But it will start softly at first, but as the car gets warmer starts. It does not do this everytime I stop either. I might go 1-5 red lights with out it. then it will do it again, though I have noticed that as the weather warms up it get worse. Sometimes it will do it once or twice at a red light, then not at the next red light. The point is that it is super inconsistant. When is starts to do it, i have tried to kick it in to N and that smooths it right ou. So it is load related. With that said it all started last week when i hadd 700LB's of fryer oil in the truck for a 20 mile trip in 90 degree heat.
Next symptom is when the light turns green and i come off the brake to the gas, it will slightly buck/miss/shudder/bind for the first 2-3 feet/seconds then smooth out fine. That is more consistant, meaning it happens ALMOST every time i set off, weather is was "missing" while i was at the red light or not. So in other words, i will be on the brake, truck is puurring like a kitten, then i go to set off, and it shudders/bucks/misses/binds. But even this does not happen every time, and does not happen when the truck is cold. but after that first "miss" it drive great...until...
The next symptom happen around 30-70mph, but cruising. lets say i am going 55mph and i give it a little gass to keep it steady. it will buck a bit, maybe 2-3 times. If i go more them about 1/4 throttle, it is fine, if i floor it it is fine. This is also inconsistant, and worse when the truck/weather is warm.
Last symptom is as inconsistant as the rest, and that is a slight lack of power. Meaning it will drive strong, and fine, then will be down on power a bit under all driving condidtions, then back to fine and so on. there is no common freguency the the power lose and it is minimal, but i do notice it.
None of these symptoms happen when the truck is cold. It drives very well actually. If i had to put the 4 symptoms in order of frequency, i would say that the taking off from a red light shudder/miss/ bind happen the most frequently, then the Shudder/miss/binding while at the red light, followed by the cruising shudder/miss/bind. All garnished with spratic light loss of power here and there.
So far i have done thes relating to this prob...
-plugs, wires, (both not ac delco but i didnt know about that until recently, and the truck ran fine for 2-3 months with those in).
-Cleaned EGR valve a bit, but it was a bit sticky when i pulled it off so i gave it a Little PB blaster which seemed to help it not stick while it was out of the car and cool, but when hot with exhaust who knows.
-fuel filter
-fuel pressure test, this one was interesting cuz at idel it is at 54psi and a WOT it is at 60psi. From what i understand those are acceptible numbers, but the spec is 60-66psi. and it is consistant. Meaning when the car acts up, the fuel pressure is not drop or raise at all. I also tested the fuel pressure 3 moths ago when i got it, and it was the same numbers.
-Trans filter.
I have done a ton of other thing to the truck (alternator, batt, all brakes all around, brake lines, fuel fillerneck, swaybar enlinks, water pump, radiator etc) none of which i think have anything to do with this issue.
Today i plan on cleaning the maf and throttle body. will let you all know if that helps.
But today I started to think it may be trans related. May torque converter? would the shaking/shuddering/miss while at the red light dismiss that though?
If the TB and MAF cleaning dont do anything, my next step is back to plugs wires with ACD brand, rotor button, and dist cap. I will also check the distributor for shaft play while i am there.
I have been reading online for days, and alot of people have a lot of the same symptoms as me, but no one i have seen yet has the Red Light shudder/miss/bind. Issue. thats whats killing me. Amy help would be apprecitated.
