Sometimes giving up is the best way to go, ehertz. I hope they find the problem quick and it's nothing major.

 

lol, my truck is just like ehertz, i dont have the diognastic thing either, and the manual i have (haynes) really didnt explain it good, i was having the same problem, it started like your but then got so bad, i couldn't even get over 1k rpms before it would die. 4crawler told me it was probably a egr leak, so i tihtened up my egr bolts, adjusted that flat head screw on the efi box, right to the left of the intake hose, and the problem got better and better untill it went away. i thought it was my fuel pump or filter also, because it was acting almost the same as it did when my ff got clogged up

 

Aint it the truth? Especially when your fingers are nothing but nubs any longer, the dog wont look at you and the wife is asking, "HOW are we going to get out of here???" .....eh chem, ...sorry, flash back to a 70 Z28 327-carb repair I was trying to do in the woods, hahaha. Luckily, a Ranger rolled up with around 800 YEARS EXPERIENCE with Chevy's, .....not 1 hour later, ..."We were ROLLIN AGAIN!" hahaha.

 

Hmm, thanks 85junk. I did have an EGR vac line loose but i fixed that...same problem. I did want to mention that when driving, I can turn it off and coast for a moment then turn the truck back on and it will run perfect for 30 seconds to a minute and then it goes back to its evil ways. No word from the mechanic yet but he is a good guy!

 

Wow, Hertz, ....sorry man!

Funny thing, here. If you read that portion of my troubleshooting or build threads, I mention many times that my truck was doing the SAME THING! It would start, cold, fine, ....then soon as in closed loop(or when it was supposed to), the truck would idle down on it's own and start bogging out. If I drove it at that point, it would kinda 'JUMP' out of it when hitting 2500 RPM or so. (it would bog, starting off up the road, then BAT OUT OF HELL after 2500 RPM, then 2nd gear, a lil bogging and by 3rd it would smooth out, but I could feel the hesitation if I'd hold the pedal steady for any time. Come to a stop......idle down again, eventually. However, when I'd restart it, it would idle fine for around 15-20 seconds, ...then idle back down and feel like it wanted to die.

As you know, 2 of my major problems were the AFM and TPS (another item that was 'done' was the IACV). I replaced all 3 and it seemed better, but the idling down didn't go away until I replaced my ECU. You probably know the story by now, that the donor ECU wasn't reading the system properly(it was throwing o2 and Knock Sensor codes, not reading those items or was set for different resistance ones, and the newer donor from the 87 I got IS READING THEM at the ECU, and no longer throwing codes.) The original threw no codes, either, but it would always want to idle down. After the AFM and TPS replacements, it wasn't as bad or as often, ...but it was still there, no doubt! Put in the new ECU and it doesn't do that any more. Still have that lil miss, but it's gonna take a scope to find something like that, ya know?

Were you not throwing any codes, Hertz? Is the mechanic going to test all the components at the ECU? TPS, AFM, INJECTORS, 02S, ....yadda yadda, lol.

Still anxious to see what he finds, .....best wishes, Hertz!

Mark

 

Reminds of the time, years and years ago, my wife and I had finished all of our town errands and office cleaning and broke down on the way home. (We used to clean offices late at night). We'd noticed the water pump in our '78 Plymouth 4wd was making racket on the way in to town and, so, picked up a new one once we got there to be prepared for our eventual trek home. Town, Fayetteville, was/is 30miles away. So, half way home, as expected, the water pump died, we pulled into the rest area, slept over night in the back, and got up early in the morn' to do the swap. I didn't have a manual on hand, so I had to go by the obvious as far as dismantling was concerned. To shorten the story, I reached a point where I couldn't figure out it all was supposed to come apart without tearing the entire front end down. After a while, I'd just about given up and knew I was going to need some help. Then, this quiet like, older fella seemingly from out of nowhere, comes up behind us to see what was the matter. I told him and he says,"Oh....you gotta take this off right there". In complete relief, we thanked him and I proceeded to pull it off. After only a few moments, we turned to thank him once again and he was gone. That was trippy! Ask and it is given.

 

In thinking about what you all, Chef and ehertz, are describing of your symptoms, I'd just like to point out that the ECU has a programmed fuel enrichment on start up. Shortly after the engine actually starts running, it adjust a/f ratio again. So, it runs fine for a brief moment, then starts bogging. No conclusions here on that, but it's a clue.

 

AWESOME! I can't count on both hands the number of times that's happened to me. Great story, Thook! Thanks for sharing.

As far as the ECU, ..not sure if you're saying 'it sounds more like something else, rather than the ECU', or if you're offering confirmation? hahaha. My truck MOST DEFINITELY is running better. And, with everything else in my rig that I've verified, replaced, fixed, etc,. ....then having changed out the original, same #'s, ....it just seems to me that the old ECU I had just had issues, maybe? lol. Very strange, I know,...as they don't often go out. However, neither do a few other things on mine that actually did, hahaha.

Good to hear from ya, Thook! WHEEL ON! ...>lemme play our theme song, lol....

Hertz, let us know asap, as, while I can't speak for Thook, I would guess he's CHEWING HIS NAILS as much as I, wondering what the mechanic finds wrong with it, lol. Jk, I don't chew my nails, ...but I AM CURIOUS hahaha.

 

Yes I keep the phone close. I cant wait. This thing has been controlling my life every day now for the last 2 months!

 

read you owners manual if you still have one..

 

huh?

 

Hahahaha, ...well, Hertz. ...like I told ya, ..."People VERY RARELY read back through a thread that's over a couple pages long". I give ya props, homie,...you did your best and you need it running, I fully understand. Couple things I might have to take it in for...I just can't figure a couple things out without a scope, more than likely. It throws NO codes, everything ohm'd and air gaped and volt'd and "at the ECU"-checks like a champ, ....but it still 'hiccups', and even a couple Master Techs have been on it and said, plain as day, "If you brought it to me, I'd say, "Nothing's wrong with it that I'll find without scoping it out", ....but most shops don't run those, and it aint free, so I've tried on my own, for DAYZZZZ, lol.

 

well if you got a broken coolant sensor that controls your ecu, your going to have problems,

if you have a missing or broken knock sensor your going to have proplems there aswell they are not cheap. i got mine at advanced auto parts 168.00 i spent.

make sure your engine time is set, and do a valve lashing on the valves, to help improve your engine quailty

 

I believe he replaced or verified both of those sensors, 90. I agree with the 'going to have issues' in those conditions... But I'm pretty sure he's addressed/diagnosed/verified signal from them. I had a Coolant Temp sensor issue for a while, ...I know they can wreak havoc!

Can't remember, but I think he set the timing and valve lash as well, ....(sorry, too many threads I'm trying to follow, lol).

Anyhow, it's at the shop now, so I guess we'll have to wait and see what the guy comes up with. I've certainly put out about 100 suggestions, hahaha. Maybe one of them was right, .... more than likely, Thook beat me to it! lol

 

oh i know how it can be... some times it just the simple thing you know.. if you stick to the basic's you prevent alot of errors down the road..

well i guess we will have to find out ..

i cant my temp gauge to go up over maybe a 1/4" past cold... when i first put the engine in the truck it was working fine but who know's the truck run fines.. no light or nothing

 

Well, that's the difficulty in internet troubleshooting.......one can't be there to see and hear what's going on. So, everyone throws in their best guesses and hopes something sticks. Some things are obvious and easy, for sure, while some things are not. These are cases of Un-EFI'd vehicles; UnEquivocally Freakin' Irritating.

 

Hmm, interesting 1990, I have the same situation. I noticed when I drove it to the shop which is about 20 minutes away, the temp never went over about 1/4 from cold. I know my temp gauge works, but I found that interesting. It is very possible that the thermo sensor is bad since I got one from a j-yard. I was throwing a thermo code, but that was because I did not have one prior!!! Once I got one that eliminated the code and my worries. I assumed that since I was not throwing a code that the sensor was good? I wonder if the truck is acting like a chainsaw would when you first start it and its cold...you hit the gas and it dies and keeps doing that until its finally warm enough to run full throttle...any thoughts anyone?

 

that sounds like your cold start sensor or your cold start injector maybe going bad..
u can take the little fuel line of the csi and unscrew like to small bolts and pull out your csi and clean it up with some carborator injector clean, and your cheathing wifes toothbrush, (she will never know) lol...

 

Not the cold start system. If you actually had problems starting when cold, then I'd say more than likely one or more of the cold start components. However, if you did have a bad coolant sensor (not sending unit), then you could also have starting issues. Usually, it's just running problems.

On the coolant sensor, you may not throw a code even if it's bad. And, generally it won't. Read the first page in this link. It's gives a very good description, using the coolant sensor as an example, of how a component can be bad and yet the ECU still does not detect a fault:

http://www.autoshop101.com/forms/h27.pdf

In short, the coolant sensor is suppose to be high in resistance when the coolant (engine) is cold. As the coolant warms up, the resistance drops and the voltage signal drops accordingly. However, if the resistance remains high, the voltage signal will remain high and the ECU will still think the engine is cold.......even though it isn't. But, the reason the ECU doesn't throw a code is because the voltage signal is still in acceptable range even though it isn't truly representative of the actual coolant temp. Now, if the ECU was to lose connection altogether with sensor, even if temporarily, due to an open in the circuit, or the voltage signal was to actually go out of range due to a short, then you'd throw a code.

Read this, also:
http://www.autoshop101.com/forms/h32.pdf

 

Thook,


YOU DA MAN! hahaha. As always, VERY informative and CLEAR AS GLASS-reading!