I have a feeling this may not get answered but I'll try anyway. 88 camaro, buick roadmaster 5.7, 5.7 injectors, knock sensors, esc module..

I recently went and picked up a chip out of a 5.7 tbi roadmaster and installed it(I think, read on) along with a few other sensors(new sensors) that were damaged. The engine would run but had a very high idle (1200+) and the throttle body/injectors made a very loud hissing sound (spraying too much fuel?).

Fast forward to today, I decided to stick the old chip back in and see what happens...I fired it up and it idles much better, around 6-700 rpm, with no hissing from the throttle body.

I'm now wondering if I didn't get the chips mixed up and maybe I've had the 305 chip in the entire time. Is there any way to i.d the chips?

 

You can ID the chips by the 4 letter code on the top of them. Note that you can't swap chips between different ECMs. Doing so will produce a fast flashing SES light and the ECM will be in limp mode.

RBob.

 

How does it run with the 305 chip in it? Does it seem to have much more power or similar to the 305?

 

^^it doesn't run great. Stumbles a bit on acceleration, dies when coasting/coming to a stop.

So I need the whole ecu? The cel light was flashing with the other chip.

 

For the record, I have that engine stuffed into an '88 K1500--that is, the swirl-port 5.7 as used in Caprice, Roadmaster, and others in '92--94 or something like that. I bought mine as a crate engine.

Uses stock ECM, uses stock prom. Runs so perfect I can't believe it.

Not a whole lot of power, but PERFECT manners and driveability in all weather at all speeds.

Fuel economy isn't the best, but completely in line with the original engine, and other folks I know have similar vehicles and we're all getting about the same mileage.

Any decent scan tool should provide Prom ID, but then you get to match that number with some Prom chart. I've forgotten what Prom mine is.

 

I ended up getting the ecu from the 93 roadmaster. Car is hard to start, runs rough, smelling unburnt fuel, and getting a code 42. I just replaced the esc module a few weeks ago, not sure what's to blame just yet but it still isn't right.

 

You have the '93 Roadmaster engine, and the ECU from the same vehicle? And it's hard to start, throwing codes, etc?

I'm wondering about the wiring harness--is it compatible with the new computer, or did GM play games with the pin assignment? What's the scan tool telling you?

 

93 roadmaster engine and ecu

I don't have access to a scan tool compatible with obd1.

Also I don't think it's a pin issue. I reinstalled the Camaro ecu and still have the same code and issues. I believe I do have a spark issue I'm just not sure what it is.

 

This sounds less and less like a modification issue, and more like a plain ol' defect.

You need access to a REAL scan tool more than ever.

 

Note that code 42 is an EST (electronic spark timing) issue, not an ESC (electronic spark control) issue. Code 43 is for an ESC issue.

Code 42 is for the distributor.

RBob.

 

Rbob-I get est and esc confused. I replaced the module inside the distributor recently due to no spark. This engine ran flawlessly in the original car.

I read somewhere than a bad knock sensor could trip a code 42, is that true? or is it always in the distributor or wiring to the module?

I agree. I'm going to look into a scan tool. I have access to a couple high dollar tools at work but I don't believe they'll work with obd1

 

Not that I know of. Code 42 can be set two ways:

During cranking, until the engine RPM exceeds 400, the ECM holds the EST/BYPASS line low. This tells the ICM to fire the plugs at the base setting and to clamp the EST line from the ECM. If it doesn't clamp the EST signal then the ECM will see the EST pulses and set code 42.

Once the engine is running the ECM sets the EST/BYPASS high which tells the ICM to release the EST line and to also use it for dwell and spark timing (now under ECM control). The ECM now counts the DRP coming in and compares it to the count of EST pulses going out. A mismatch will cause code 42.

RBob.

 

Cool I'm gonna see if I can't figure this out this weekend. Thanks.

 

Problem solved. The connector that you disconnect when setting the timing was unplugged. I'm not sure what it's called. No codes now.

The hard start/stumbling/dying when braking seems to have been due to not having enough gas in the tank, which means my fuel gauge is wrong. The car finally died and wouldn't fire back up until I added gas, now it runs much better.