Full parts cannon and still runs rough

[Blp378]

So I’ve tried all I know to do before making this post. However, I have a 92 tbi that was running rich, stumbling, loss of power, and randomly dies at stops. Some times it runs fairly decent although not great other times it will barely idle. Condition seems to be getting worse. So far I’ve replaced fuel pump assembly, fuel filter, o2, egr and solenoid, map, tps, rebuilt throttle body with new regulator and injectors, distributor cap and rotor along with plugs.I bought new wires this morning and knock sensor those are going on this afternoon. I don’t have access to a Scan tool, but the truck shows no codes. It did at one point show an egr and map code but those have been replaced and no code present. I’ve swapped the ecu from two other trucks also didn’t change the problem. If the truck is stationary it revs just fine but trying to climb a hill it’s almost like a 4 barrel carb that won’t open the secondary’s. I only have hand tools a basic amp clamp multimeter and that’s about it. Haven’t checked fuel pressure but I don’t see how that could be the problem. I’ve made sure all of the grounds are connected while I’m changing the wires today I will go through and makes sure they’re clean. Aside from that I’m at a complete loss. Engine has approx 6k miles on it bought from summit several years ago. While I’m on that topic I should mention the truck has sat for 8 years after I put the motor in.

Thanks in advance,
Brandon



Edit to update: changed wire definitely had a dead wire. The rest were good high reading I had was 13k ohms I believe the book says 30k is the max. So on that note the truck sounds healthier. Still has a rough idle in park and even worse sitting in drive. Revs helps it to clear up but it’s searching a few hundred rpm. My rtv has apparently dried out on me so I have to make a trip to town to change the knock sensor. Also forgot to add that both temp sensors have been changed.

 

[Erik the Awful]

Check to make sure both injectors are actually spraying a nice cone of fuel into their bores.

 

[TylerZ281500]

did this problem exist prior to the new engine? what is the new engine, factory replacement kind of deal?

have you checked to ensure the grounds at the waterneck and back of the head are good, no breaks. the one on the back of the head will do some wierd stuff as your facing if that breaks. took me a long time to figure that one out on my old 93.

ground straps too are important, grab some off amazon for cheap and traingulate, frame, engine and body if youre uncertain

 

[Blp378]

did this problem exist prior to the new engine? what is the new engine, factory replacement kind of deal?

have you checked to ensure the grounds at the waterneck and back of the head are good, no breaks. the one on the back of the head will do some wierd stuff as your facing if that breaks. took me a long time to figure that one out on my old 93.

ground straps too are important, grab some off amazon for cheap and traingulate, frame, engine and body if youre uncertain

Yes it’s a factory replacement. All of these problems are new. I deceided to put it on the road again and doing so I changed the fluids plugs etc ya know the basics. And it ran great for a few weeks then I had an injector decide it’s wanted all the pressure all the time which hydro kicked the engine at first key on. So I got the fix and it’s just going down hill from there. I will order the ground strap kit and go from there

 

[Erik the Awful]

Your injectors get power all the time, and the ECM controls the duty cycle by switching the ground on and off. If your ground wire is shorted to ground, your injector will run non-stop. Check your wiring harness. The injector connectors and wiring are usually pretty crunchy, but you can get replacements fairly cheap.

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[TylerZ281500]

im not saying order it off the bat but id just check them. usually like 10-20 bucks though which is safe insurance for probably corroded almost 40 year old straps.

you hydrolocked it? not enough to wash a cylinder or bend a rod though? wondering if this has anything to do with injector circuit

 

[Just Nobody]

Check the IAC plug- My 92 had that plug in the wrong orientation as a result of the lineup pin/tab was broken and the plug looked like all was ok but it was 90 degree out . I bought a new plug and rewired into harness, all was good after. Also check the distributor module and the part that the rotor screws onto, under the cap, might be bent or cracked. Also check the injector spray pattern, I use a flashlight, for visual, to check the spray pattern shape and injector pulse

 

[Blp378]

im not saying order it off the bat but id just check them. usually like 10-20 bucks though which is safe insurance for probably corroded almost 40 year old straps.

you hydrolocked it? not enough to wash a cylinder or bend a rod though? wondering if this has anything to do with injector circuit

Yea I thought the starter took a **** so I replaced it and same thing then thought it might need shims but nope. When I noticed it was an injector is when I turned the key the last time and heard the injector spray fuel on the prime. That’s when I looked and the throttle body was full of gas. Pulled the plugs spun it over a bunch. Replaced the injectors and it ran great for the first few days then all of these problems started happening and over time they’ve gotten worse I’ve replaced half of the parts because they were bad.

The ground straps are fairly corroded, they have that green tint all the way up them so I’m going to replaced them for sure.

So how long should it take for the ecu to start learning a new fuel table? A few miles or days?

 

[Schurkey]

I don’t have access to a Scan tool,

GET access to a scan tool, and other diagnostic equipment.

Use the scan tool to verify ALL the sensors, and computer outputs.



What is the initial ignition timing? Does the spark advance work? Will the ignition coil reliably fire a spark-tester calibrated for HEI, when the coil is hot from running, and sprayed with a mist of water from a squirt-bottle?

If the truck is stationary it revs just fine but trying to climb a hill it’s almost like a 4 barrel carb that won’t open the secondary’s.

What is the fuel pressure?

Is the exhaust system plugged? If the engine misfires long enough, it'll melt the catalytic converter. If it runs bad long enough, it'll plug the catalyst with soot.

the truck has sat for 8 years after I put the motor in.

Did you run 8-year old gas through the engine?

My rtv has apparently dried out on me so I have to make a trip to town to change the knock sensor.

WHY do you need RTV to change a knock sensor? Use thread sealer, not RTV Silicone.

Among the best thread sealers is Loctite/Permatex 592, and available at most auto-parts stores.

I looked and the throttle body was full of gas. Pulled the plugs spun it over a bunch.

Perform a cranking compression test to look for cylinder(s) with poor compression, perhaps due to broken rings, popped head gasket, or bent connecting rod(s).

So how long should it take for the ecu to start learning a new fuel table? A few miles or days?

Several miles, although it should begin learning as soon as the computer goes into closed-loop operation. Could be days depending on how far you drive in a day.

 

[Just Nobody]

GET access to a scan tool, and other diagnostic equipment.

Use the scan tool to verify ALL the sensors, and computer outputs.



What is the initial ignition timing? Does the spark advance work? Will the ignition coil reliably fire a spark-tester calibrated for HEI, when the coil is hot from running, and sprayed with a mist of water from a squirt-bottle?


What is the fuel pressure?

Is the exhaust system plugged? If the engine misfires long enough, it'll melt the catalytic converter. If it runs bad long enough, it'll plug the catalyst with soot.


Did you run 8-year old gas through the engine?


WHY do you need RTV to change a knock sensor? Use thread sealer, not RTV Silicone.

Among the best thread sealers is Loctite/Permatex 592, and available at most auto-parts stores.


Perform a cranking compression test to look for cylinder(s) with poor compression, perhaps due to broken rings, popped head gasket, or bent connecting rod(s).


Several miles, although it should begin learning as soon as the computer goes into closed-loop operation. Could be days depending on how far you drive in a day.

Scan tool would be great, it an OBD1 and the paperclip and count the blinks is the only way I know how to read codes.
Even using the paper clip trick it still might shine some light on the issue.