The dreaded flashing Check Engine Light

[bottomline2000]

What do you mean your trims? Was that causing blinking cel?

Check all of you plug wires and make sure they are fully seated. I had a plug wire pop off once and it caused a blinking check engine light.

Just saw your latest post..I would check your o2 sensors or it could be your cats clogging. U need a way to datalog the truck to see what the sensors are doing. I'd be curious to what your fuel trims are doing. If it's going lean it could be the fuel pump..

Ltft should be around 0 or 1..ideally less than 8. . If it's around 12 u have a problem. Plugged cats will run it up to 25..The computer is dumping fuel and trying to compensate for a problem.

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[iamdub]

More flashing CEL info:
http://www.tahoeyukonforum.com/threads/2001-tahoe-blinking-check-engine-light.28786/


That is not fully correct. My one code reader only saw p0300 but my other one read p0306. So, based on what I have seen, it's dependent on the code reader.

We can only go off of what he has told us and the chances of him or whatever shop he brought it to using the same exact scanner as yours that doesn't read the individual cylinder misfire codes is pretty slim. He mentioned previously in this thread of having multiple shops run diagnostics on it and at least one used a Tech2 which is entirely capable of pulling all codes. In his other thread on this same issue, he mentioned "generic" misfire and "P0300". Not jumping your case, just trying to stick to the known facts, or at least what the OP has revealed.

 

[Sgtduckyboy]

We can only go off of what he has told us and the chances of him or whatever shop he brought it to using the same exact scanner as yours that doesn't read the individual cylinder misfire codes is pretty slim. He mentioned previously in this thread of having multiple shops run diagnostics on it and at least one used a Tech2 which is entirely capable of pulling all codes. In his other thread on this same issue, he mentioned "generic" misfire and "P0300". Not jumping your case, just trying to stick to the known facts, or at least what the OP has revealed.

Gotcha! Good point

 

[M1Gunner]

Thanks again everybody for all the insight. So far, still havent figured it out. Im gonna try to get it hooked up to run live diagnostics. Ill list current work done vs my next thoughts and continue listening to feedback lol. Thanks a lot guys!!!

Work done:
-new battery
-new alternator
-new belt
-new plugs
-new coils
-new wires
-cleaned maf
-cleaned throttle body
-oil change
-trans fluid and filter
-fuel filter
-air filter
-pcv valve
-fuel pressure regulator
-diffs and t-case fluid replacement
-fuel pressure test (idle and neutral acceleration)
-crankshaft position sensor
-im sure theres a few that im missing

Thoughts of work still to do:
-catalytic converter
-oxygen sensors
-fuel pump
-vacuum test (intake manifold?)
-timing?

I dunno. A lot of the stuff done, I dont mind too much as it clearly wasnt maintained by last owner and needed a lot of it. Starting to get quite expensive and frustrating now. Truck is supposed to become my daily driver but I have been driving my tundra til I can trust this. Appreciate all tye suggestions and help you guys are giving. Sorry, some 9f this stuff is taking a little while and I cant check or update until i have the funds and time to do certain parts. Im fixing as my finances allow lol

Lol please dear lord, check your o2 sensors!!! Especially the upstream! These are older vehicles but stop throwing parts at it... all the money you just threw at your rig, you could’ve bought a moderate scan tool to check live data either done some research or throw the readings at us to interpret. O2 sensors are just messengers but sometimes those cheap messengers, just like women, throw some crazy mixed signals and (don’t shoot the woman) but you gotta shoot that messenger though everyone says not to. Especially the downstream cheapos too... they’ll start gettin busier than a cat tryin to cover crap on a marble floor!

 

[HiHoeSilver]

Lol please dear lord, check your o2 sensors!!! Especially the upstream! These are older vehicles but stop throwing parts at it... all the money you just threw at your rig, you could’ve bought a moderate scan tool to check live data either done some research or throw the readings at us to interpret. O2 sensors are just messengers but sometimes those cheap messengers, just like women, throw some crazy mixed signals and (don’t shoot the woman) but you gotta shoot that messenger though everyone says not to. Especially the downstream cheapos too... they’ll start gettin busier than a cat tryin to cover crap on a marble floor!

 

[iamdub]

Lol please dear lord, check your o2 sensors!!! Especially the upstream! These are older vehicles but stop throwing parts at it... all the money you just threw at your rig, you could’ve bought a moderate scan tool to check live data either done some research or throw the readings at us to interpret. O2 sensors are just messengers but sometimes those cheap messengers, just like women, throw some crazy mixed signals and (don’t shoot the woman) but you gotta shoot that messenger though everyone says not to. Especially the downstream cheapos too... they’ll start gettin busier than a cat tryin to cover crap on a marble floor!

But the downstream (after cat) O2 sensors do nothing for fuel trims or how the engine is running. They only monitor the efficiency of the catalytic converter(s). A problem detected by them would result in catalyst efficiency code(s). If his symptoms continue long enough, the cats may be damaged by being burnt and/or clogged, which THEN may lead to catalyst efficiency code(s).

 

[M1Gunner]

But the downstream (after cat) O2 sensors do nothing for fuel trims or how the engine is running. They only monitor the efficiency of the catalytic converter(s). A problem detected by them would result in catalyst efficiency code(s). If his symptoms continue long enough, the cats may be damaged by being burnt and/or clogged, which THEN may lead to catalyst efficiency code(s).

...yes, indeed.

 

[rockola1971]

Ive figured it out....OP has GREMLINS! Choot'Em!


Id first pop the hood (at night) with engine running look around for any visuals of spark going to ground. The flashes will be a dead give away if this is happening. (leaking spark plug wire, crack in ignition coil). Then right before its time to change the oil id drop a quart of tranny fluid in it and let it idle for 15 mins and then drain and change the oil. DO NOT DRIVE AROUND WITH TRANNY FLUID IN THE OIL!

 

[Motojoe86]

Lol please dear lord, check your o2 sensors!!! Especially the upstream! These are older vehicles but stop throwing parts at it... all the money you just threw at your rig, you could’ve bought a moderate scan tool to check live data either done some research or throw the readings at us to interpret. O2 sensors are just messengers but sometimes those cheap messengers, just like women, throw some crazy mixed signals and (don’t shoot the woman) but you gotta shoot that messenger though everyone says not to. Especially the downstream cheapos too... they’ll start gettin busier than a cat tryin to cover crap on a marble floor!

I just swapped them all out a few ho7rs ago lol. Check engine is on but I am gonna drive it through the week so it gets a run cycle and I'll update if that made a difference. Thanks!

 

[Motojoe86]

Well, changed upstream o2s and now its running worse then before. Idle is dipping a bunch and has died out couple times... Think its time for new vehicle