I have a 2017 Yukon Denali with about 116,000 miles. I just had all of the fuel injectors replaced. After replacement I still felt like I had random / intermittent rough idling. When codes were check I ended up replacing the Mass Air Flow sensor. Codes went away but I still have random rough idling. I had the codes check but it was only a couple miles after reattaching the battery and driving down to my shop who replaced the injectors. I just replaced the MAP sensor tonight to see if that does anything. I have not had a check engine light on since the injectors were replaced. I do not really see the RPMs moving when I notice the rough idle and there are times it’s more aggressive of a rough idle. I’m hoping it’s the MAP sensor but wondering if anyone else has any other thoughts. Also wondering about a locking tab on the MAP sensor. When I went to replace the sensor the locking tab was broken off. I didn’t replace the sensor and the plug did snap back on I feel like securely. How nervous should I be that there is not locking tab and can you replace just the connector without doing the whole harness if it’s that big of a deal?
2017 Yukon Denali MAP Sensor Question & Rough Idle
- Thread starter Adam5SS
- Start date
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Welcome to the forum from Virginia. Did your mechanic look or find any old stored codes? Replacing injectors at 117k seems early but you never know. What type of gas are you running? I’ve heard of rough idle associated with AFM/DOD but if it’s a new problem that wouldn’t make sense.
So I switched to premium gas around 100k miles. Before that I’d get like 415 on a full tank of mostly highway. When I switched to premium more like 460-480. When I replaced the Mass Air Flow I’m now at like 535 the last two fills up. When the code was run before new injectors. Check engine like would come on randomly. I was getting tons of mis fires in one cylinder. It would stop after so many key cycles but then a week and a half later same thing. So I swapped all the injectors since the labor for all was an extra half hour over just one. When I got it back I was getting codes I’ll attach it here. I had 3 codes one day and then 4 then next. However when the 3 codes showed the engine was running when the 4 codes showed up the engine was not running the car was in accessory mode. I don’t have a scan tool the shop used theirs but to me I would think the engine needs to be running to show active codes but I’m not sure. After I replaced the mad air flow sensor no codes but I had the negative battery off over night and literally connected it and drove probably a mile to the shop where there were no codes. I’m not sure if it was run enough to show codes or not. It was still doing it for the week I drove it and no engine or any lights in so I just swapped the MAP sensor. I don’t feel like I notice any sluggish behavior and my MPG seems to be going up with the new sensors. I’m actually starting to wonder if 1. I’m being overly sensitive to the Random what I’m calling rough idle because of the check engine light being on(since I’m not seeing any RPM really change) and it’s intermittent. It’s a V8 and I can’t say that it didn’t always have a bit of a rough idle compared to my 2011 Acadia Denali. Might be just the fact that it’s an 8 cylinder or I’m wondering if its possibly an engine mount going bad also. I’m heading to the shop today to have them pull codes to see if I have any.
On the screen shot I added the three bottom codes were the original ones after injectors with the engine running. That screen shot is from the following day before MAF sensor replaced and with the car in accessory mode engine off.
Attachments
I had a service manager describe the sensation of a rough idle this way. He asked me if it felt like when you’re fishing and you get a nibble on your line, just a little tug. Then it starts to feel like a bigger tug but when you start driving it goes away. He said it was normal but modern cars shouldn’t feel that way even with AFM/DOD.
