Westers Garage has been doing programing for me for some time. Have an 89 K1500 with 7747 computer, used to run Edelbrocks TBI to MPFI conversion system but changed to Vortec heads and Edelbrocks Hi Flow tuned port setup, TB flows 785cfm. This is an older problem for me even with the original Edelbrock tune, the check engine light comes on in cruise on the highway- code 32 which seems to be a common problem. I have been told that the GM EGR valve is a 'balanced' valve and since my exhaust works so good its screwing up the valve with not enough back pressure. I looked into part numbers and the '91 vette EGR is different than the Camaro EGR valve, I was thinking that since the vette exhaust is so much better than the Camaro it may work for me- also the vette plumbing is similar to mine in that EGR tube comes off the header. The code was shut down so the light wouldn't come on, but it seemed to impede EGR function- right now under heavy throttle there is pinging, with the code off pinging was present even at moderate throttle. In the past I used 94oct all the time and now am using 89oct- so if the tuning wasn't great the 94oct is now no longer a crutch. My mechanic suggested that I get a 'universal EGR' with the disc orifaces and experiment with the disc's- I really don't want to tear down the manifold multiple times. I know there is alot of experiance out there- hope you can help me out. davefarr@telus.net

 

Talk to your mechanic about a negative backpressure EGR valve.

 

From 1988 IROC 5.7L V8 manual.

EGR valve is negative back pressure type.

Code 32 means that the EGR diagnostic switch was closed during start-up or that the switch was not detected closed under the following conditions:[list=1][*]Coolant temperature greater than 80 degrees C (176 degrees F). [*]EGR duty cycle commanded by the ECM is greater than 48%. [*]TSP less than wide open throttle (WOT) but not at idle. [*]Codes 21, 22, 33, 34 not present.[/list=1]
All conditions above must be met for about 4 minutes.
If the switch is detected closed during start-up, or if the switch is detected open when the above conditions are met, the "Service Engine Soon" light will remain "ON" unless the switch changes state.
Use the Code 32 Diagnostic chart to determine if the EGR valve, EGR solenoid, and or the diagnostic switch are faulty.

If the awitch is always open, or closed you can recalibrated, if it isn't broke, or buy another for about $50.

 

Running a 180 Supertat with a 454 big block aluminum rad and vette electric fans- if anything I'm being overcooled- there were three rads that fit this truck it came factory with the smallest and I probably overshot the mark by putting in the biggest- I was running somewhat hot.

This coding- only on the highway in cruise control on the flats where the conditions are constant for a number of minute-sengine light stays on.

Honestly I am guessing at the code because of a past history with this condition, when A&B are shorted the computer flashes code 12 and nothing else- the computer doesn't save this code- will have to put a scanner on the truck to confirm the code when it happens- this was the case before. No other codes.

I have been told that the computer is commanding the EGR then watching the O2 for changes- this isn't happening- then codes.

I really don't have the equipement or knowledge to do this work- is there anybody in southern BC or northern Washington that does vehicle tuning? Or is this Prominator a worthwhile investment?

 

If you're using the basis of a factory TPI control system with the Edelbrock aluminum parts, the ECM is going to be looking for a state change from the EGR temperature switch when the ECM commands the EGR open. If the ECM is from a TBI, it will be looking for a MAP change. If it's an aftermarket ECM, contact the manufacturer.

 

The application is a 89 GM truck with original 7747 TBI computer driving a left and right bank of 8 injectors. Went for testing today because the $23 is cheap for a dyno test, failed at idle but NOX was really good proving the EGR is functioning- looks like the cat is dead and running fat at idle. Huge difference with a tank of 94oct really shows there is good potential in the TPI for a truck application. Still has pinging problem- will try to get a datalogger on this somehow. Got a scanner on the computer before shut down and confirmed the phantom code 32.

 

had hooked the vacume lines as per dwgs found on some tpi site, didn't know that camaro's had a solinoid that activated the charcoal cannister- so was trying to run cannister and egr off front tb port. routed full vacume to egr and left cannister purge on tb. egr works and no service engine light on the hwy.