Guru's! New 85 GM crate motor, runs rough, misfires when hot, shows up upon restart!

[tpaul]

Hey all,
I've got an 85 GN with a new GN crate motor. The motor has been checked out, lubed, and gone through cam break in by a local reputable shop. I installed the motor and trans and assembled all parts above the "long block" myself.
While the car was parked before the new motor was installed I added: 87 ecm with a translator chip, LT1 maf, MAF Translator, Big Mouth cold air intake, fuel pump hot wire, Walbro fuel pump, green strip injectors, adjustable fuel pump,heated O2 senser, and a used fuel injector harness.
The fuel rail, valve covers,pipes, and other parts where sandblasted and powder coated. Other parts like the throttle body and intake were blasted and painted. Items like the throttle body were totally dissassembled before plasting and painting.
Problem: the car runs great from cold. Once it gets up to temp for a long time, or the car is at temp and you shut it off and restart, it runs rough. The car runs like a cylinder is dead. For lack of better words... it's a putt, putt, putt kind of sound. This seams to die down at around 40 mph.
A check of the spark plugs showed that the #2 cylinder was much cleaner than all the other plugs. #4 cylinder was mid-way between all other cylinders.
I have changed to new plugs, wires, ignition module, and coil pack. None of these changed the issue. I've ruled out the ignition system as a problem. The crank and cam sensors were new with the crate motor.
Sorry for the long post... Any Ideas???

Thanks,
Tim

 

[esinger]

Hi, you stated the fuel rail was blasted, maybe there's something inside blocking the fuel flow on that side of the fuel rail.

Just a thought.

 

[tpaul]

I considered that, but the fact it's only at temp made me think otherwise. Am I incorrect? As all things change with heat, would a change in temp effect glass bead? I figure it would be the same hot or cold. I maybe wrong.. it wouldn't be the first time.

Thanks,
Tim

 

[Jerryl]

Do you have a scantool?
If you do, post some numbers like; Codes, IAC, TPS, temp sensor, MAF, O2's

 

[tpaul]

TurboLink 2.13 numbers while running rough at idle:

IAC - 39# (I know... high)
LV8 - 36#
TPS - .46v (again, high I know)
O2 volts - 578 mv
MAF - 3 GPS
Block Learn - 118#
O2 Delta Counts - 45#
Man. Air Temp. - 138

Engine speed - 850 RPM
ESC Counts - 0
Spark Retard - 0.0
Prom ID - 8080
Coolant temp - 203
Road Speed - 0
Battery Volts - 12.5
EGR Duty Cycle - 0

ECM Mode - Norm
Batt status - Norm
Clear Flood - No
Learn Ctrl. - On
Asynch Mode - Off
Mixture - Lean
Loop Status - CLSD
P/N switch - On
TCC - Off
P/S Switch - Off
3rd Gear - Off
4th Gear - Off
A/C Request - Off

 

[Jerryl]

Your MAF reading is low. You are looking for 6-7 @ idle.
A reading of 3-4@ idle usually indicates a disconnected MAF but you are not getting any SES codes (? ?), so if it is plugged in it requires replacement (I am making the assumption that the ECM wires and connectors are in good working order)

Adjust the IAC and TPS and get them within spec.
You will be amazed how much difference it will make.

The temp is pretty high as well, unless you have the stock T-stat still in the car and/or somthing else going on with the coolant system. You may want to start thinking (depending on your goals) about replacement with a 160F unit.

Now for the good news ......... All other numbers look ok. :biggrin:
BLM will come up with a new MAF and TPS/IAC adjustment.

 

[tpaul]

Thanks for the reply,
I was under the understanding that with an LT or LS MAF and a MAF translator the MAF values would be cut in half. So my 3 on Turbolink actually equals a 6 with the stock 87 MAF. The MAF was a brand new piece bought from Full Throttle.
As for temps, I'm running a 160 thermostat. These reading were captured a few months ago. I did have a problem dialing in my electric fan for awhile. I've got that under control now. The temps are running where they should be.
Dialing in the TPS and IAC has been a major pain in the butt, but I know they need to be fixed. I guess that's a problem we all deal with! Those are just the least of my worries right now. I need to be able to drive this darn car!
Thanks for your input! I'm glad to see that everything else seems in line! I've got a list of things to fix, I don't need any more! I never should have let this car sit for five years!!! Just in the past week the turn signal flasher and alternator have gone out. It's a good car, but it seems like something is always going South on me. I guess we can't complain... not too many people can say they own a 20+ year old car that goes up in value evey year!

Thanks again,
Tim

 

[Jerryl]

.....I was under the understanding that with an LT or LS MAF and a MAF translator the MAF values would be cut in half. So my 3 on Turbolink actually equals a 6 with the stock 87 MAF. The MAF was a brand new piece bought from Full Throttle.

As for temps, I'm running a 160 thermostat. These reading were captured a few months ago. I did have a problem dialing in my electric fan for awhile. I've got that under control now. The temps are running where they should be.

Are you running the extender chip? If you do, yes, the MAF #'s would be cut in 1/2. (I should have asked ) Post some recent "hot idle numbers" if you can.

 

[tpaul]

Thanks again, yes, I am running an extender chip. I'll try to take the car out today and record some new numbers.

 

[tpaul]

Here's the new numbers:
IAC - 20#
LV8 - 43#
TPS - .44v
Intergrator – 122#
O2 volts - 507 mv
MAF - 4 GPS
Block Learn - 120#
O2 Delta Counts - 78#
Man. Air Temp. - 98

Engine speed - 775 RPM
ESC Counts - 9
Spark Retard - 0.0
Prom ID - 8080
Coolant temp - 174
Road Speed - 0
Battery Volts – 11.9
EGR Duty Cycle - 0

ECM Mode - Norm
Batt status - Norm
Clear Flood - No
Learn Ctrl. - On
Asynch Mode - Off
Mixture - Lean
Loop Status - CLSD
P/N switch - On
TCC - Off
P/S Switch - Off
3rd Gear - Off
4th Gear - Off
A/C Request - Off

 

[boostmaster]

Here's the new numbers:

Battery Volts – 11.9

This may be your problem, low battery voltage does crazy stuff to these cars.

 

[tpaul]

I was looking at those numbers and wondering... I just put in an old alternator with a new diode. The first alternator was @ 12.5 volts. The "new diode" alternator is @ 11.9 volts. What should I see for voltage at idle?
What causes voltage to be low? Is it the regulator or something deeper? I've had to replace a few diodes in this cars life. These KB headers sure do a number on my alternator!

Thanks

 

[Jerryl]

.......... The first alternator was @ 12.5 volts. The "new diode" alternator is @ 11.9 volts. What should I see for voltage at idle?

What causes voltage to be low? Is it the regulator or something deeper? I've had to replace a few diodes in this cars life. These KB headers sure do a number on my alternator!

Thanks

You are looking for 13+ volts.
Check ALL the grounds.
The grounds to the body are notorious for causing low voltage readings, especially on a scantool.

Also, connect a VOM on the back of the alternator and see what the voltage is @ idle.

 

[tpaul]

Getting the new motor to fire initally was a huge pain (no spark, I tried everything I could!) I had to trailer it back to the shop. Kevin and his crew finally tracked down multiple problems after many shop hours! It kicked my butt to defeat. In his words it kicked his butt too, but being a GN, he couldn't let it leave the shop without running! Bad pins at the ignition module and a couple other problems. At the same time they added a couple redundant grounds. Grounds should be good at this point.
I think you may very well be on the right track with voltage though. After your last post I fired up the car, again it was running rough. I threw the battery charger at 40 amps on there and the car smoothed out pretty quick. I'll need to hook up T-Link and take a look at the voltage numbers to confirm.
This may be my excuse to get that nice new 140 amp Powermaster alternator.
Thanks for the help, hopefully this will be the solution!!!

 

[Jerryl]

......... This may be my excuse to get that nice new 140 amp Powermaster alternator. .......

Be sure the alternator is a direct "bolt on". :smile:

 

[tpaul]

I went to the Powermaster web page and they have one listed specifically for the 84-85 GN. Hopefully they are correct and not just guessing!
Jerryl, are all my other new numbers where they should be?

 

[tpaul]

Thanks for the help guys! I just ordered the alternator from Summit. We'll see when it arrives. If it comes by Friday, I won't have it in until at the earliest Saturday night (due to work.) I'll send and update once it's installed! Stand by, if this doesn't do it, I'll need more help!

Thanks again,
Tim

 

[Jerryl]

Here's the new numbers:
IAC - 20# (10-20, Looks ok)
LV8 - 43# (Load parameter - Looks about right)
TPS - .44v (.42 - .46)
Intergrator – 122# (Short term adjustment will change constantly; 128 +- 10)
O2 volts - 507 mv (Looks ok)
MAF - 4 GPS (Stcok maf 5-7 - Looks ok)
Block Learn - 120# (Long term adjustment; 128 +-10)
O2 Delta Counts - 78# (O2 CC - Make sure it cycles continuesly 0-255)
Man. Air Temp. - 98

Engine speed - 775 RPM (Programed in the chip, controlled by IAC)
ESC Counts - 9 (WIll increase when knock is detected)
Spark Retard - 0.0 (0 = good )
Prom ID - 8080
Coolant temp - 174 (looks good - will depend on weather, AC, speed, etc)
Road Speed - 0
Battery Volts – 11.9 (Look for 13+)
EGR Duty Cycle - 0

ECM Mode - Norm
Batt status - Norm
Clear Flood - No
Learn Ctrl. - On
Asynch Mode - Off
Mixture - Lean (Will toggle back and forth, indicating ECM control)
Loop Status - CLSD (Will change with a new chip like TT which is "Open Loop idle)
P/N switch - On
TCC - Off
P/S Switch - Off
3rd Gear - Off
4th Gear - Off
A/C Request - Off

.......... numbers .... where they should be?

See above
Some short explanation provided, hopefully, this is not redundant knowledge.

 

[tpaul]

Awesome info!!! Thanks so much! I was crusing around the gnttype.org site for the correct parameters, but I couldn't find them when I was looking. This info is much appreciated, as is all your help!
Is 9 on the ESC counts bad considering the car was never above idle?

Thanks again,
Tim

 

[Jerryl]

Awesome info!!! Thanks so much! I was crusing around the gnttype.org site for the correct parameters, but I couldn't find them when I was looking. This info is much appreciated, as is all your help!
Is 9 on the ESC counts bad considering the car was never above idle?

Thanks again,
Tim

Nothing to worry about for now.
Usually, the starter will set the ESC module off. (False KR)
Here is the link. Quick Reference Page For the '86/'87 Turbo Regals and '89 Turbo T/A

Edit
Yes, the numbers apply to the HA cars as well. :smile: