Injuneer

I can tell you with absolute certainty that you will not be able to even start to solve the problem until the injector size programmed into the PCM matches the injector size installed in the engine. Without that being firmly established, you can't work on anything else.

If the PCM has been tuned for stock (24#/HR) injectors all along, and you have actually been running with 47#/HR, and then with 36#/HR injectors, it is very likely that your spark plugs are badly fouled. They will need to be inspected and replaced if fouled with carbon.

And, if you were in fact running oversize injectors, there is a good chance the rich mixture cause fuel to leak past the piston rings and contaminate the oil. You need to check the oil for a gasoline smell, and/or a diluted appearance. DO NOT RUN THE ENGINE UNTIL YOU RESOLVE THIS, and replace the oil if it is contaminated. Hopefully there was no ring/cylinder wall damage, or damaged bearings due to the dilution.

As noted in the post immediately above this one, download the FREE scanning software linked in this thread:

https://www.camaroz28.com/forums/com...95-lt1-874306/

You can build a cable for $20 or buy one for about $50. It is a necessary investment.

With regard to your statement " I don't have the resources to tune it every time I do something to it it to make it start.".... only you can control this. If you can't afford to get the PCM tuned, DO NOT MAKE CHANGES THAT REQUIRE A TUNE. Basic, common sense. Not all changes will need a tune. If you don't know whether a change requires a tune - ASK FIRST.

Note that while a mail order tune may have a large initial expense, most tuners will make subsequent minor changes for a very low cost. A good tune shouldn't be as expensive as buying two sets of injectors, and would be money better spent.

You also need to answer the questions that are asked:

-What are the full specs on the cam - inlet/exhaust duration at 0.050" lift, lobe separation angle (we'll assume the lift you put in your first post is correct, unless you tell us).?

-What brand is the new Optispark?

-has anyone, at any point, scanned it for codes?

-has anyone, at any point, checked the fuel pressure?

-what are ALL the engine and exhaust modifications? Was it "rebuilt" to stock, just the cam upgraded, ????????

-you indicate "rechecked tune", and mentioned pcmforless. Who "checked" and have you paid anyone to tune it?

And from my point of view, in response to this post:

Lose the attitude, or you will be gone from the site. We want to help you, and I asked you serious questions. I don't see an insult anywhere.

RMACE

ok premier automotive of west jordan sent my PCM to PCMforless to tune it. The only thing i know that was changed was the specs for the new cam. Nothing else, to my knowledge was changed. It wasn't untill after the PCM was re-installed that Premier found out what injectors are in the car. I didnt know anything about the car because i bought it "as is". The previous owners bought it after the engine was allegedly rebuilt by the owners before them and could not find the docs applying to that rebuild. SO all that being said, I ASSUME that nothing has been changed in the PCM from stock other than cam specs. If it has, I am not personally aware of it. I have emailed Bryan J Herrter of PCMforless and asked what injectors the PCM is programmed for and he reffered me to Kieth Wenzel. He asked when the tune occured and i told him and am waiting for a reply. I dont know if they would even have record of it considering that in my research I have found that to tune an LT1 PCM, the current programming must be saved in a file outside of the PCM, modified and then used to replace the old tune with the new modified tune. Is the new tuning saved? I dont know. If not then I doubt I can find out that info. now to update.

My wife and I used instruction found online to test the ignition system using an ohm meter. Being an electrician by trade I am VERY familiar with this tool. However the one I have is primarily used for AC but has a DC feature for 1000 ohms. since I need it to reach 3-10,000 for 5-7000 ohm readings, I dont trust it to help. I thought maybe the coil or ICM was faulty and had Autozone test the ICM and it turned out good. The coil was replaced, in hope that was the issue (During my testing i removed the 2 7.5 amp fuses for the injectors to fuel out of the equation). Once the new coil and ICM was re-installed and fuses replaced the car started and ran beautifully for about 10-15 seconds then coughed sputtered and died. starting a few more times it steadily got worse. I disconnected the TPS and opened the throttle and it began to run smoothly then the idle jumped drastically from 500 to 2100 RPM and i shut it down to prevent over-reving.

This tells me, a greenie, that the injectors are too big and the PCM is not compensating for it through the O2s.

Now, if i install an adjustable regulator and turn the fuel down to 25 psi, will this compensate for the 36s presently installed without creating any other fuel related issues? my goal is to switch the 52 mm twin throttle body to a 58 mm twin and add headers later this year. My thinking isthis, if i lower the PSI it will compensate for the time being and when i add the new TB an headers i will have the ability to turn the PSI up with outh retuning again. Is my thinking sound or am i off track? i am open for suggestions.

RMACE

-What are the full specs on the cam - inlet/exhaust duration at 0.050" lift, lobe separation angle (we'll assume the lift you put in your first post is correct, unless you tell us).?

(
__________________________________________________ ______________
Basic Vehicle Info:
Year 94

Model F

VIN: .2G1FP32P1R2126096

Broadcast:

Engine Size: 5.7L
__________________________________________________ ______________
Drivetrain Info:
Trans Manual

Built Transmission? stock

Gear stock

Current Tire Size stock


Stock Tire Size stock

Shift firmness 0

Torque Convertor stock
__________________________________________________ ______________
Fuel System:
Fuel Octane 91

Injector Size stock

Injector Make .

Injector Rating . PSI

Delete 9th Injector? No

Disable DOD? Not Applicable
__________________________________________________ ______________
General Info: Constants
Speed limiter? Remove

Rev limiter? tuner's choice (recommended)

Thermostat stock

Remove Skipshift? remove

Idle tuner's choice (recommended)

Trouble Codes?

Elevation? .4500

Towing? no

Electric Fan stockfan

__________________________________________________ ______________
Engine:
MAF

MAF Ported? No

MAF Descreened? No

Throttle Body stock

Cold Air Intake stock

Intake Manifold stock
__________________________________________________ ________________
Exhaust:
Exhaust stock

Catback aftermarket

Remove Cat highflow
__________________________________________________ ______________
Engine


Camshaft comp 07-304-8

Duration .210 , .220

Lift .334, .342

LSA .114

Advance .
__________________________________________________ ______________
Head Info
stock

Compression stock:1

Displacement . CID

Rocker roller

__________________________________________________ ______________
MISC

Nitrous no

Nitrous Amount

Timing Retard Box? no

Wet or Dry? )

-What brand is the new Optispark? (i dont know it was purchased and installed by Premier automotive. im sure aftermarket.)

-has anyone, at any point, scanned it for codes? (yes 3 times and no codes)

-has anyone, at any point, checked the fuel pressure?

-what are ALL the engine and exhaust modifications? Was it "rebuilt" to stock, just the cam upgraded, ???????? (clevite bearings, Mohle rings, comp cam, roller rockers and springs, double roller timing set)

-you indicate "rechecked tune", and mentioned pcmforless. Who "checked" and have you paid anyone to tune it? (I emailed PCMforless and asked whatr they did and they confirmed that they didnt mess with ignition. nobody else has touched it)

RMACE

I apologize but this is why I had the attitude. Im asking for help, not to be talked to in this manner. If knew what was wrong or what I am doing I would not be asking. Ive asked half a dozen people for help only to get nowhere and be down over $1800.

I apologize for the attitude and greatly appreciate any help.

RMACE

OH sorry missed the fuel pressure question. yes premier did and said it was within specs

RMACE

THANK YOU. Thats why Im here. Ive been trying to fix this for over 6 months and Im very frustrated

slick1hunting

I'm going to somewhat repeat what has already been advised and add my two cents. First off the tune has to match the injectors that are in it and should not be ran until it does. Second re read what Fred said about likely haveing fouled plugs and washed out oil. Also the o2 may also be fouled out. Its possible all that could take out the cat. The point I'm making is the fueling effect has too much depending on it to be correct to not have the tune match the injector. Fuel pressure and injector size and possibly even brand will be critical to getting the tune corrected. Using the adjustable fuel pressure regulator is a bad idea and often the source of problems in proper running engines. I advise against getting a bigger throttle body until you have good ported heads and a matching big cam otherwise just asking for more issues and really no extra power. If the cost of the tune and hardware is too much lt1pcmtuning.com has a loaner program with retunes and would be a good idea as you can use his hardware to reflash pcm and log results and then he will modify the tune a couple times. You will likely be paying for a rebuild if you continue to try things without the tune being set for the proper injectors and fuel pressure. Look at the place I suggested and read the various aspects of tuning and fueling and you will get a better understanding.

RMACE

Thank you slick. That was put in a way that makes sense. I will change the oil before going any further as injuneer suggested and scratch the adjustable regulator idea. Next will be new injectors. AS for the cat, it was deleted by previous owners.

slick1hunting

LT1 PCM Tuning - Tips & Tricks for DIY Tuning! that will give you a better understanding of how the pcm works. Also Fred has a good writeup too (injuneer) and if his web page is working again is likely a link from his profile and the one linked previously will have most things lt1 related. Listen to Fred and try to do as he says as he is a very knowledgeable guy and will likely save you a lot of money and heartache.

slick1hunting

No dont get new injectors so quick. The injectors either need to match what its tuned for or the tune needs to match the injectors. I would suggest having the pcm read to know what its tuned for first. Then opt to get injectors that match that or change the tune to match injectors you have.

RMACE

Ok, so listen to Fred, change the oil, have the pcm read and match the tuning and injectors. Got it.

RMACE

injuneer,

i have emailed PCMforless asking about re-tunes. Thanks for this info.

"Note that while a mail order tune may have a large initial expense, most tuners will make subsequent minor changes for a very low cost. A good tune shouldn't be as expensive as buying two sets of injectors, and would be money better spent."

Injuneer

...

RMACE

?????

RMACE

ok fred heres what Ive done per your recomendations.

changed oil and filter
new bosch III 24# injectors
checked all vacuume hoses, no leaks that i can find
PCM is tuned for 24# injector per PCMforless

now,
car runs but low power and exhaust manifold heat up red hot after about 5 minutes while temp gauge read about 160
while in gear revs build very slow (6 spd man)
I only drove it to the gas station and back 2 blocks away and put in about 5.5 gals 91 octane and found a pin hole in the heater hose going to heater core so I parked it for the night

SO is it normal for manifold to heat up this bad and why is it still running so poorly?