5.7L TBI stalling and low idle help

[James Archer]

ordered module and thermal paste! Will be here Friday. Might even invest in tuner pro also if this doesn't fix anything.

 

[PlayingWithTBI]

ordered module and thermal paste! Will be here Friday. Might even invest in tuner pro also if this doesn't fix anything.

That may or may not cure your problem but, with proper data logging, you should be able to find it. Some links for TunerPro RT v5xxx etc...

http://www.tunerpro.net/downloadApp.htm

http://aldlcable.com/aldl.asp

You can find your definitions here as well as on TunerPro's website
http://www.gearhead-efi.com/gearhead-efi/

And some research
http://www.gearhead-efi.com/Fuel-Injection/forumdisplay.php?27-TunerPro-Tuning-Talk

 

[Schurkey]

ordered module and thermal paste! Will be here Friday. Might even invest in tuner pro also if this doesn't fix anything.

More parts replacement without proper diagnosis.

But...you might get lucky.

 

[James Archer]

More parts replacement without proper diagnosis.

But...you might get lucky.

Any suggestions on how to diagnose that? Being that most of the parts are all original I don't have a issue replacing parts being that I'm doing a full restoration on my truck. When I did the research about the code 90% of the people having the issue I am having has to do with that part of a small percentage of people mention the computer.

 

[Schurkey]

Get the scan tool, use it. It's "possible" but CRAZY to try to fix a computer-controlled engine/trans/dashboard/ABS/Airbag system when you can't communicate with the computer that's making all the decisions, possibly with faulty data from a sensor or wire-harness problem.


Look at the data stream. "Codes" can be important. Data stream is CRUCIAL. Compare to values in the shop manual. What is the official procedure for the Code 42 you're seeing?

Check for codes, write 'em down--then clear the code(s) and see what comes back.

Did you ever fix the low oil pressure?

Did you ever verify that the fuel pump relay is working properly? Does the pump have a 2-second prime when the key is turned from "Off" to "Run"?

For the record...HOW OLD IS THE O2 SENSOR? Of all the sensors and actuators on a computer-controlled engine, the ONLY one I might replace "just because it's old" would be the O2 sensor. They get lazy as they age--they may still "work" but they don't react quickly like they should. You'd see this on the scan tool as a low number of "cross-counts".

Dear Old Dad bought a '98 Monte Carlo. The O2 sensor was old enough to buy liquor, but it only has about 35K miles on it. (It was original!) I changed it a week or two ago, I was getting 6 or 8 cross-counts; I'd rather see 20+.

 

[James Archer]

Get the scan tool, use it. It's "possible" but CRAZY to try to fix a computer-controlled engine/trans/dashboard/ABS/Airbag system when you can't communicate with the computer that's making all the decisions, possibly with faulty data from a sensor or wire-harness problem.


Look at the data stream. "Codes" can be important. Data stream is CRUCIAL. Compare to values in the shop manual. What is the official procedure for the Code 42 you're seeing?

Check for codes, write 'em down--then clear the code(s) and see what comes back.

Did you ever fix the low oil pressure?

Did you ever verify that the fuel pump relay is working properly? Does the pump have a 2-second prime when the key is turned from "Off" to "Run"?

For the record...HOW OLD IS THE O2 SENSOR? Of all the sensors and actuators on a computer-controlled engine, the ONLY one I might replace "just because it's old" would be the O2 sensor. They get lazy as they age--they may still "work" but they don't react quickly like they should. You'd see this on the scan tool as a low number of "cross-counts".

Dear Old Dad bought a '98 Monte Carlo. The O2 sensor was old enough to buy liquor, but it only has about 35K miles on it. (It was original!) I changed it a week or two ago, I was getting 6 or 8 cross-counts; I'd rather see 20+.

I appreciate your help and ton! I ended up going to the motor guy I use for all my race stuff. He's an old timer so I figured he would have some suggestions. He suggested I put 6 degrees base timing in it and change the injectors and change the igniton module to the acdelco I ordered. ( To me it really seemed like it was flooding out when I rolled into the accelerator. I did order the scan tool and will use the same laptop I use to do my tuning on my bikes.) The O2 sensors are definitely going to be replaced when I start designing the exhaust. The only issue it currently has now is if I roll into the throttle it hesitates just a split second then goes. I just drove it to fill the tank and all around town and it was great. I'm expecting it to have some stutter due to the y-pipe leaking real bad, O2 sensors and the transmission hunting for overdrive. I plan to service that as well.

As far as the low oil pressure, I only had that issue when the RPMs where low. Which is to be expected.

The fuel pump does in fact prime for 2-3 second.

 

[Schurkey]

The O2 sensors ... ...O2 sensors

There is only one.

The fuel pump does in fact prime for 2-3 second.

That's good news. The ECM can control the fuel pump via the fuel pump relay.

As long as the ECM is also turning on the relay when the pickup coil is sending signal to the ignition module.

 

[DiGiTaL D]

I have a similar problem, though nowhere near as bad. When in gear, idle speed, turning the wheel often causes the engine to die. This is a big problem when maneuvering my trailer around in the driveway or into a campsite. This week, I noticed a similar behavior when the A/C compressor kicks on when stopped at idle speed at a stop light. My truck is bone stock, and the only thing significant I've ever done to the engine is plugs/wires/cap/rotor. I also replaced the TBI gasket once a couple years ago trying to solve this problem but it didn't help. Any ideas?

 

[Schurkey]

I have a similar problem, though nowhere near as bad. When in gear, idle speed, turning the wheel often causes the engine to die. This is a big problem when maneuvering my trailer around in the driveway or into a campsite. This week, I noticed a similar behavior when the A/C compressor kicks on when stopped at idle speed at a stop light. My truck is bone stock, and the only thing significant I've ever done to the engine is plugs/wires/cap/rotor. I also replaced the TBI gasket once a couple years ago trying to solve this problem but it didn't help. Any ideas?

Connect a scan tool, look at commanded idle speed vs. actual idle speed. Perhaps the IAC or the IAC wire harness is defective.

How old is the O2 sensor?

 

[James Archer]

New ignition module is in. Drove it around for a little and it backfired like crazy. So I decided to take the base timing back down to 0 and right back to the same issue. At low RPM it wants to stall out and when I first get onto the gas it boggs down and then picks up a little