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Howdy, just about to lose all my hair here. Only 25 and it isn't genetic.

Problem: Driving along fine all day, pull into driveway and it dies before I can turn the key off.

Symptoms: Starts up fine however unable to pull codes (no check engine light...used to come on occasionally), but very shortly afterward will surge extremely bad until it eventually dies. If lucky enough to get going without stalling, it will bog out under load and backfire. Unplugging vacuum to map I find tons of vacuum on that line--idles very high while disconnected but stops surging however then dies seemingly random. Fuel delivery seems fine and injectors spray strong and evenly, and seem to be reacting well to throttle..

History:
-New Remanned Engine with new intake manifold from reputable shop, installed by yours truly. Less than 10k on engine since installed. Cat delete, A/C delete, SMOG/Air pump delete, EGR can't be doing much given the latter? And running with no oil pressure sensor as the wire disappeared, was never connected on old engine, and in terms of engine function it only serves as a backup power to fuel pump in case of relay or pump failure , so I've read (also been running fine for 6 months like this, checking oil and monitor engine coolant temp religiously)

-The new stuff:
Battery, Alternator, Spark plugs, wires, entire distributor assembly, ESC module, IGN Coil. MAP sensor, IAC Valve, TEMP sensor (on intake manifold), Fuel pressure regulator assembly, Fuel Pump and Screen, TB gaskets, O2 sensor, all fuses on under-dash panel.

-The not-new suspect stuff
Knock sensor

Temp sensor on drivers side of block

Why did my CEL stop coming on in any circumstance? Not even on initial
ACC power--this led me to believe ECM but plugged in an ECM from a 90s 305 TBI to see if CEL comes on and still nothing, despite having checked every single circuit on fuse panel for short with a test light between power lead and positive terminal. This whole thing with no CEL at all led me to believe the Remanned ECM was toast so I ordered one. Have yet to install the proper replacement ECM but I would have thought the other TBI's computer would at least turn on the CEL on ACC power. . .

Injector leads appear nicked and exposed, plug connectors appear melted (been running fine like this for 6 months, but I ordered new ones and will eventually make proper solder/shrink splices to replace mechanical crimp splices...still doubtful that this is the core issue given they have been like that for months and the truck has had no issues because of it.

Fuel Filter appeared new when I bought the truck so I have not replaced it, however if I end of replacing the injectors I will be sure to change this out with a new one. It's in the mail too. Still doubtful this is the core issue, as the injectors spray fine, seemingly.

Would there be some in-line bus fuse someone suggest I check given these symptoms? I did a test light test for shorts to ground but I guess that would not reveal a simply held open circuit due to a blown fuse...:embarrass

Does all this info together generate any ideas or suggestions (serious ones) that I can handle being a wannabe? I have spent way to much money so far in the hope that this expensive method of troubleshooting would lead to less and less problems in the future. . . probably a rooky mistake, but I don't have time to get too serious with troubleshooting, although I have now been reading on how to make your own ALDL cable--but not sure that will help given the lack of comms between the ECM and CEL. . .I also have reason to believe the Bulb is not just simply burned out but have not verified this.
 

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Basics - check fuel pressure, vacuum and initial timing.

Really sounds like fuel pressure problem, but there is no need to skip checking anything basic. Your method of checking vacuum is inadequate. Need a gauge to see if it's steady. If ALL of that is good, then check for bad grounds - start checking for voltage around the engine bay with a multimeter. If any is found, then you need to rectify that.

If still no resolve, then report back.
 

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Oh boy so many mods it's hard to pick a spot and start. One that leaps out is the oil pressure wire your description of what it does is totally wrong, it is not a back up to the fuel pump it is a shut off. It's function is to notify the computer that the engine is running. The computer is programmed to shut off electrical power to the fuel pump 8 seconds after it first senses the ignition system is switched to on without seeing oil pressure in that period. It is also programmed to maintain the fuel pump on as long as it sees oil pressure and to shut it off in the absence of oil pressure. This is a safety device intended to shut the fuel pump off if the engine fails to start or keep running. If the engine starts and runs without this wire properly hooked up it's a powerful message that the electrical system has been tampered with. That has to lead to the thought of what the else is mickey moused.

EGR doesn't give a crap about the air pump the AIR pump is there to combust unburnt mixture as it enters the exhaust manifold. This is the result of late ignition timing being the cause and the reason is protection from overheating the catalytic converter with excess unburnt mixture. The EGR recylces some exhaust gasses during cruise to lower combustion temperatures so less NOx is produced. It is not functional at idle or WOT. Failure of the EGR valve is pretty messy as it usually fails so exhaust is bleeding into the intake all the time, this really screws up the idle if the engine will run at all. Failure is usually carbon holding the valve open all the time or of the diaphragm leaking, this latter one really screws the engine up.

Lack of a CEL is either telling you the light bulb is burnt out or the computer is toast.

Fuel filter function is not a quality of how nice it looks on the outside. The fuel filter plugging up to the point of reducing flow leans out the mixture everywhere, for a while the O2 sensor will correct this but eventually the reduced fuel flow to the injectors is more than the O2 sensor screwing around with the computer's injector duty cycle can correct.

Damaged wiring at the injector especially with signs of overheating and physical damage to the wires is an indicator that either the injectors are using too much current which would happen if they were using too much duty cycle, or if the wires are damaged the injectors can't get enough current to operate correctly which overheats the wires around the physically damaged area as it acts like a resistor where the higher the resistance against the current draw makes heat.

Your set up appears to have plenty of issues to choose from as singular or multiple in causes. You're just going to have to fix this stuff.

Bogie
 

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EGR Silionoid



On that 5.7(and some 5.0's) you have a vacuum hose coming off the throttle body going to this then another hose coming off this going to your actual egr valve. There is also a foam piece which likes to deteriorate and clog the sensor.

This will not throw a code, will not set off other codes. Do not pass go but do get out that $200 for a tow bill.



This will cause a bogging which will become progressively worse to the point the truck will not even start.


A way to tell is that you will only have power until you let up on the throttle. This sensor is telling the computer to space the injector pulses out because the egr is clogged and your sending bad air into the engine. As long as you don't let up on the throttle from idle the thing will not stall once you let up you will need to "pump the throttle" to have the thing get any speed.

I been there a few times back in the early 2000's.




I hated when first trouble shooting it. But now I love this sensor.
It has been the reason for me buying 4 s10's and 2 full size tbi trucks at this point when the engine was "junk". I have literately stumbled to get the truck down the road as not to be a total bag about it. Pulled a good one from my tool bag plugged it in and the truck ran great all the way home.

This use to be a stealership part at $120 or so and of course was special order(back in 2001 took me 2 weeks which is why I know about pumping the throttle to get the thing to accelerate). But the part can now be bought at Napa for under $20.

https://www.napaonline.com/en/p/MPF319226

Buy the part disconnect your battery for 5 minutes remove the one screw holding the plug in then bracket then plug in the new part and start up the truck. If your vacuum lines are still plastic replace them with new rubber line as those plastic lines can have micro cracks.


I would also check the egr valve with a mighty vac to make sure it is not stuck. But I have owned almost 20 tbi trucks. They are pretty simple to play with as long as you dont mess around putting some crazy cam or heads on them. But this one sensor will cause you headaches and is something to just replace every 30000 miles or 5 years.

The foam is what kills these things. You need to keep that foam clean. If you degrease your engine or take a hose to your engine remove this sensor or at least cover the foam up. Some engines have a plastic cover the size of a quarter which prevents the foam from being drenched directly and as you can imagine that foam last longer. But if not just peek at the thing during oil changes to make sure the foam is still there.
 

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Discussion Starter #5
Latest new ECM, SES not burnt, still no blinky. Also new fuel filter. No change

Howdy,

Great comments, very appreciative. Here's a good and long-winded update.

The mood is tense--all three of my vehicles are not operational at this point. Renting a car to get to work.

Not for the sake of argument, but more so to prompt deeper investigation regarding the function of the oil pressure sensor located on the rear driver's side of the block--I too thought it logical that it would cut the engine in the event of a low pressure signal but I distinctly remember reading that beyond displaying pressure on the dash this sensor is actually just a backup power source to the fuel pump to limp home--it involves extra long cranking time in the event of a bum fuel pump relay, and that it serving to kill the engine on low pressure is a common misconception on this engine (also corroborated by the fact that I've been running for 6 months with it disconnected, no?) I agree fully though, I ought to get my new one hooked up, I just can't for the life of me find the wire/terminal for it. Doubt it has anything to do with this current issue though.

Today I replaced the fuel filter--produced no change. The relatively new pump seems to work fine as the gas was back up to the engine in no time. Having not used a fuel pressure gauge yet (don't have one) I'm still confident I didn't get a bum fuel pump...and the spray patterns are still looking top notch when the engine is running (feathering throttle to keep from dying). If it comes down to it I'll get a proper test going and report back on pressure.

I pulled the EGR solenoid mentioned above and pumped compressed air through-- no change but will still try a new one since the solenoid could still be dinked. When reinstalled I got no change. I verified the EGR valve is not stuck (I just crammed by finger in and worked it a bit. Very little change in idle while doing so. Does that mean something is clogged?

Went around engine with a propane bottle torch and just let the gas blow around all my lines, it was very hard to tell if there were any changes in idle speed or quality related to a vacuum leak or the computer reacting to some other fault. Idle speed cranked right up at one point but a sharp whistle indicated to me the IAC was doing its thing and it was not a line sucking in the gas. Might try again but at this point I can only get the truck to idle temporarily with the map line plugged.

I pulled the dash apart and verified the SES light bulb is not burnt out--not just visually as I briefly put 12 volts to it and it lit right up (turns out it isn't a check engine). I also installed the new computer with my old prom. Still not getting a SES light on with ACC or trying for diagnostic mode with jumpered A and B on the OBDI. Rest assured, I removed the main fuse from my amp system, removed the stereo, disconnected the negative terminal all before monkeying with the new computer. But oh great, it's looking like a wiring overhaul now. . . wish my daily truck hadn't died while I was installing this engine and I may have been less rushed and got some new cables in there.

I will try a new EGR solenoid, get my new injector connectors properly spliced on, set my timing light up with the tan circuit open to verify 0-2 degrees, and with it connected to verify smooth advance/retard, replace the second coolant temp sensor, knock sensor, and let yall know what I find. Just afraid to bother with trying to read codes via ALDL and software since I assume that if I can't get a communication to the SES light the ALDL cable won't help either--happy to be corrected on this though.

One other thing I noticed, and I am unsure if this is a symptom of the core issue or if it is the core issue, that a sharp whistle occurred when the relatively new and definitely clean IAC activated (is it supposed to open or close at idle? can't remember) and the engine seemed to run better....but maybe this new control valve is not operating as smoothly and as often as it should, but I would guess that is a sign of poor voltage and shotty old wiring...

KBO all.
 

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There is a procedure for setting the IAC when it is replaced - google it and you'll find it.

Unplugging the map sensor is the only way it will run is a sign. The fuel table at atmospheric pressure is not the same as when it's at 15-20" of vacuum. You need a method of monitring live data to see what's happenning IMO. Or a test vehicle to swap you map sensor onto. Does your EGRV hold vacuum? It should.
 

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Discussion Starter #7
Follow Up

Welp.

To answer the latest post,

I did do the IAC procedure when I first installed it. It still operates when a signal is sent to it (ie. after the engine warms up. Coming down from High RPM. . .

The new MAP could very well be a dud since that sort of thing has happened to me in the past (AC Hellco)

Still waiting on new knock sensor. I read this little mic being toast can affect the auto-timing. . .

I'm not sure how the EGR solenoid not operating properly could affect the engine this severley; doesn't it just let a small amount of exhaust into the throttle body for cooling purposes at cruise speed?

The freshly soldered and heat shrunk injector connectors did nothing..

Double checked the fuse shared by the lighter and horn was good as I read some folks say the ECM or bulb is on the same ciruit

Still perplexed as to why the bulb doesn't come on....maybe the printed circuit board of the dash is toast. . . Other lights on it seem to be fine. . .

I might be without money, a job, and a girlfriend by the end of this but boy I sure can't wait for the part where I can explain what the issue was.
 

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Discussion Starter #8
SOLVED

If any readers care

The issue was in fact the computer--forgot to swap one of the chips into it from the old one. Still no SES light though....indicating a wiring issue I suppose.

Truck was spitting a code 52.

Also new fuel injectors, resetting tps, and resetting the timing made for the best throttle response I've had out of this relatively new (remanned)engine.
 

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SOLVED

If any readers care

The issue was in fact the computer--forgot to swap one of the chips into it from the old one. Still no SES light though....indicating a wiring issue I suppose.

Truck was spitting a code 52.

Also new fuel injectors, resetting tps, and resetting the timing made for the best throttle response I've had out of this relatively new (remanned)engine.
The truck is running - GREAT! How about a job and the girlfriend? If no and yes, then you need to go on a job hunt. If yes and no, then you needed another woman anyway - if she won't put up with some car issues, then it's time for girlfriend trade in, hopefully trade up. If no and no, then get to work hunting. If yes and yes, then happy day :thumbup:
 

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SOLVED

If any readers care

The issue was in fact the computer--forgot to swap one of the chips into it from the old one. Still no SES light though....indicating a wiring issue I suppose.

Truck was spitting a code 52.

Also new fuel injectors, resetting tps, and resetting the timing made for the best throttle response I've had out of this relatively new (remanned)engine.
Great to hear it's running, another weird one for the books.

Bogie
 
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