Hey Folks,
I put a '95 3.4L into my '87. Only the block and heads are from the 3.4L. I have all externals my attached from my 2.8L.
On day 3 after my successful completion, the idle just went highly above average for me without any changes to the car mechanically. The exhaust went a little strong too. The ignition timing is set to 10 btc as it should be.
The pcv, tps, egr, idle speed sensor, and fuel pressure regulator are fairly new. The O2 sensor which is fairly new did get saturated with trans fluid during assembly and I simply wiped it off (Maybe this is causing a problem?).
I did install my HyperTech Thermomaster chip today, after the high idle problem occured. I tried using my scanner for the car to get readings, but it said it was unable to connect with the vehicle computer. Don't know if that is from the new chip being installed. Will have to put the old one in to see if the same connection problem occurs. This is a problem that is giving me a headache because I don't know what is left that would cause this elevated idle.
Any suggestions would be greatly appreciated.

 

What is an "idle speed sensor"?

Is your CEL (AKA SES) on flashing or solid while the engine is running?

From you saying that the scanner can't connect to the car, means that it could very well be in limp home mode.

You might need a new ECM. If it is indeed in LHM. I had an ECM die sorta recently, first one actually, that only had LHM working, would not read from the MEMCAL at all.

 

I'm sorry, I meant the "Idle Air" sensor on the top of the throttle body.

 

UPDATE: I found the cause of the high idle this morning. My EGR hose was split at the connection, not causing a good enough seal. Also, The EGR Solenoid tubing was broken off at its base.

 

87InRecovery: I know this off of your topic. But I'm curious as to how much stronger your 3.4 runs compared to your 2.8? I've been planning on doing the block swap once my 2.8 expires but I could never find anything saying how much performance was improved with a cam and headers and how well the ECM reacted to those changes.

 

Hello,
The swap was extremely easy first off. Nothing at all was questionable or confusing. I can't exactly remember the horsepower difference between both stock engines; I believe it is around the 50 mark, maybe more. I installed the Crower Stage 1 CompuCam, which has a 114 degree cam lobe separation, giving the engine more torque and fuel economy. It is very good, no problems. The headers really give it a better sounding exhaust combined with my MagnaFlow Cat Converter and Muffler. I did install the HyperTech ThermoMaster Chip, along with the fan switch and themostat. All in all, my new engine sounds a lot better and the performance is a remarkable increase. I haven't done any dyno testing for camparison. The original engine ran poorly due to internal sludge, etc.... All in all, it exceeded my expectations and I'm happy with it.