1995 Ford F-150 Supercab
4.9L (300ci) IL 6
5 speed Mazda trans.
MPI, Speed Density
65k miles
Mods in signature

Greetings,
I have a problem which I guess started about a year ago, but only recently became an everyday problem. At first, the problem only happened on a restart while cold. I would leave for work, stop at the corner for coffee and a donut, and upon trying to restart, the engine would surge 1 or 2 times, and then die. It was as if the IAC was suddenly unplugged. I would turn off the ignition, and restart, and all was well. This only happened once or twice a month at first, and it never did generate a code. Now, and for the past few weeks, the problem has changed a little bit, although it will sometimes still stall. Now, at every cold start-up, and occasionally at warm start-up, the engine will be 3 or 4 seconds into running, and the MIL will flash once as the idle drops several hundred rpm. 99% of the time, it immediately recovers, and presents no drivability problems what so ever. The other 1% of the time, it acts like the original problem I described. Everytime, regardless, it will either restart fine on the second attempt, or will recover while still running, and has no other symptoms until the next attempted restart. Since the more recent problem developed, there is always a KOER code (I believe it's 14) that translates into no PIP signal. This is what I do for a living, and I'm stumped. I have cleaned the IAC several times, and reset the ECM after each one. I have adjusted and replaced the TPS because it read too jumpy when tested for resistance. I have tested the MAP, IAC, and ECT sensors repeatedly, and they always fall within specs. I have disconnected the ECM at the harness and performed every test I could find to inspect the engine wiring harness for shorts or opens. I have run a compression test, and all cylinders were within 4% of each other, and were well within range. I have performed a complete tune-up, with all new parts. I have used my OTC scantool to diagnose the PIP code, and have used the ALLDATA flowcharts, and everything reacted or tested perfectly. According to my results, I do not have a problem. Until I try and start it. My info is in my signature, and is accurate except for the plug wires, which are now brand new NAPA, and the plugs, which are now stock gapped Champion Truck plugs. Replacing them didn't effect the problem, but the truck is not as peppy as it was before the parts swap. I plan on swapping back, but I want to isolate this problem first. The only thing I can think of, that I have not yet tried, is removing the JET chip. It has really surprised me with it's performance until now, and I keep thinking it's something else, but I don't know. I opted for the JET chip when Mike told me he would need my ECM in order to burn one for me.

If anyone has some experience with a problem like this, or has some good input, I would really appreciate hearing it.

Thanks for your time.

Take care,
-Chris

 

I'm just kidding ... I told you that I owe you one and I hope that I can help !!

Chris, I was thinking the chip as well. Neal had a similar situation with his truck, it would stall and then start right up after. What he did was remove the chip, check the connection for cleanliness and then re-installed the chip. Make sure that you put a good piece of tape to hold the chip in too. I think what he found was the housing of the ECM wasn't bent in far enough and was causing a problem. Try this and see what happens.

Have Fun & Keep on Truckin'
Dean

 

Thanks Dean. That is my plan for tomorrow, I was just hoping to avoid it.

Take care,
-Chris

 

the chip connections would be my guess also . i deal alot with building pc's and the contacts get dirty sometimes and the pc's doesnt even realize the other part is there . also did you check the grounds to the ecm harness?

 

Thanks Ray. I have gone over the ground connections, and guess I must face the probability that the chip is causing my troubles. I will let you know what I find.

Take care,
-Chris

 

Seems to me that if it were the chip, you'd have this problem constantly. The fact that it's only [mostly] on cold start-ups make me think it's something else. Seems you've checked everything on the intake side- how about the fuel and exhaust (emissions) areas? Could it be a leaky injector or bad O2 sensor?

 

yep , could be a hardware conflict .

 

Thank you for the replies. I belong to an online community known as iATN, which is made up of several thousand ASE certified mechanics worldwide. I posted this question to them, and this morning have received 11 replies, so far. The suggestions are all over the place, but the two most frequently mentioned are a defective EEC relay or damage to the O2 sensor, causing it to read over 1.0 volt, and sending it into self test mode. While these suggestions sound logical, I don't understand why they wouldn't continue to cause drivability problems. Same thing with a hardware problem. I will look into them all, though. Today the Santa Ana winds are creating havoc with my sinuses, so I may have to put this off until tomorrow, but I will let you know what I find. Thanks again for the suggestions!

Take care,
-Chris

P.S. FWIW, last night around 11pm, I went out for a late dinner, and the truck started fine, no surge at all. That was the first time in weeks that had happened. Go figure.

 

just a thought . if the o2 sensor had been damaged and done that . wouldnt it do it all the time?

just trying to help . you know a hell of a lot more about this then i do . i know that for a fact . thanks to you my truck is back to running the way it should . i would not have been able to get it fixed had you not been there .

 

Since the O2 sensor must reach a certain temperature to function, it may be the transitional phase (cool to hot- nonfunctional to functional) where it is malfunctioning.

Also, could a leaking injector be dumping fuel into a cylinder then subsequently the catalytic converter? If so, couldn't this cause a brief "out-of-range" value for the emissions system (O2 sensor) until the excess fuel can be burned off.

 

Ray-
Hey, you're the one who got your hands dirty, I just had to type a few words.

Nomo-
You intrigue me. I will test my fuel pressure again and see how fast it bleeds down. Your logic makes sense. It would also explain why the problem doesn't usually occur on warm restarts.

I have received a few more replies from iATN, including one who swears it's my K&N getting oil on my MAF. I guess he skipped the part where I said it was Speed Density. Anyway, the majority is leaning towards a damaged O2 sensor circuit. I was unable to get anything done today due to the high winds, but they are supposed to subside tomorrow. I have a few things to look at.

Thanks again!!

Take care,
-Chris

 

I had a problem with my 02 sensor where I would be driving down the road and it would start to spudder and buck and then about 1 minute later it would return to normal. Five minutes down the road it would act up again, took it into the dealership and they threw it on the computer and we watched the voltages until it would swing high for a long period of time (well over 1 V) and then it would go straight to 0 V for another long period of time. When it does this, it will put a code into the computer, can't remember what they were but the codes did say O2 sensor reading high and low. Since you aren't getting any codes, I still suspect the chip connection with the ECM. More thoughts I guess.

Have Fun & Keep on Truckin'
Dean

 

Could be bad intake seals.

 

Haven't you been reading the posts from the K&N haters? It IS oil on your MAF. You ruined your truck putting in a useless gimic. Paper is safer, and will provide the utmost in power potential.

There will be no more discussion in this thread until you replace your MAF, and put a paper filter in front of it.



On a serious note, I had a similar problem for a brief period. Always on a restart, regardless of whether the truck was up to temp. About a week later the battery finally gave up the ghost.

I really see no logical reason why a weak, dying battery would cause this.... BUT it has never happened since I put a new battery in. I'm sure you have access to some strong newer batteries, it's worth a shot.

 

Not sure where you are at with this, but I had a couple of thoughts...could still be the IAC. Perhaps it is clean, but starting to go bad or have a bad connection inside of it. Aneasy way to test is when it dies give half throttle when you try to start & see if it starts like a carbed engine. I helped diagnose a bad one on my Turbocoupe that way. I've seen EGR's cause surge/start problems as well & not give a code so you may tryin playing with bypassing it for a short time. o2 sensor could be, but I'm with the others thinking it would happen all the time. Last idea would be engine temp sensor? I've seen cold start problems related to a bad temp sensor that is stuck in "warm" mode & causing the ECU to adjust the fuel mixture & cause an engine to do all kinds of goofy crap without throwing a code.

Hope this helps & doesn't confuse the matter more.