Buckeye88

Let me start off by saying that I think this forum is terrific and I've been able to fix multiple issues on my 85 just by looking through the different areas of the forum. Great knowledgeable group. I also want to say I have ordered an FSM (both books) but won't have them for another 2 weeks.


Now my issue, the engine is still running very rich and now seems to have a miss when in first gear but smooth's out after shifting to 2nd and up. Although I do have backfire issues when I let off the gas in all gears. I adjusted the TPS, was at 0.72 and is now at 0.54. Replaced the plugs, wires are next week. I have multiple codes 32, 34 and 43.


Questions:
1. For 1985 is code 43 Knock Sensor? I've seen multiple definitions listed for code 43
2. Code 34 - should I start by cleaning the throttle body and replace the MAF relay? Where is the MAF relay on an 85? All diagrams I can find when looking online pop up for 88 and up. When I look in those spots the relay's are not there.
3. code 32 states to replace the EGR switch. Is this the vacuum switch on the passenger side rear side of the plenum? I can't find a good diagram for 85's.


I've also corrected a few leaks but when I put it on stands the other night it started dripping a clear fluid. I can't find where it's coming from or what it is. I know it's not coolant or oil. Clutch fluid is where it should be and power steering fluid level is right where it should be.


I wanted to be able to drive it this week since it finally isn't raining in Ohio. But with the miss I'm worried about a bigger problem.


Thanks all in advance

85vegasvette

i an have an 85 myself been chasing a 33 maf sensor code, the relay is behind the bread box, you canfinde them for $100 on up, 85 is a one off year. i replaced the maf sensor, rewired the pigtail to the maf and still chasing... gonna re-wire again, anyway give it time and patience ..and beer and whiskey...and a spot on your head to scratch while gaxing at your babay going..wtf...lol but its worth it

Buckeye88

Thanks, getting the beer and whiskey stuff down while working on it!


Does the '85 just have the burnoff relay or a MAF Realy and Burnoff Relay? I've seen multiple statements about the '85 being different from the other years. lots of conflicting information. I need to get that FSM

Not4spd

Our 85 is throwing code 43 as well which is listed as Electronic Spark Timing circuit- low voltage. It also shows electronic spark control-circuit problems. Once we fixed the TPS code by adjusting the voltage, code 43 went away. Engine light came on again last night while driving and I haven't had a chance to check it. I'm willing to bet it is code 43 popping up again.

From what I have read on the forum code 43 is knock sensor related. People were able to get rid of this code by doing a few things:
replacing the knock sensor
loosing the knock sensor because it was to tight
Repairing wires going to the knock sensor

Subscribing to see what others might say.

xrav22

Code 42 is Electronic Spark Timing circuit in my book.

code 32 is exhaust gas recirculation circuit
says to: check the vacuum source and all vacuum lines. Check the system electrical conectors at egr and ecm. Replace egr or ecm as nessesary. I cleaned mentioned connectors and mine were really oxidized.

code 34 Mass air flow:
says to Inspect the intake system for vacuum leaks, clean the throttle body, check the
maf connections. Replace the maf relays. Replace ecm. If it is a relay the only one is behind the crash pad.
I would clean and spray maf and connectors with maf cleaner.

code 43:
Knock sensor ciruit: book says:Check the ecm for an open short to ground, if nessesary reroute the harness away from other wires and the spark plugs. Replace the knock sensor.

I had all these codes before and cleaning the ecm connectors and all of the connectors for that matter solved 75 percent of the codes. My ecm and alarm connectors were REALLY
Oxidized. No new codes over a year.
Good luck

Buckeye88

Quick update: I was able to fix the miss and I believe the code 43. The boot on the plug wire for #6 cylinder was basically melted down. I can't find details on when the PO last replaced them (those cheap heat paper receipts fade in a week). I also found an exhaust leak on the passenger side. Hoping it's at the flange and can be fixed with a new set of bolts.


Drove it to work today from Akron, OH to Canton, OH about 14 miles all highway. Check engine light about half way to work. Once parked, I turned it off and restarted and the check engine light was off. The oxygen sensor is only on the driver side, so the exhaust leak shouldn't be leading to code 32 should it?


Can't wait to have my FSM next week.

warrior4jesus

Greetings from a relocated Ohioan. Good luck with your car I hope you have the best luck getting everything sorted out.

Dennis L Brooks

I would try cheap and easy first on the code 34 - MAF. Remove the passenger side hush panel under the dash -- 3 or 4 screws- unplug coutesy light. There will be 2 connectors into the ecm and one square type connector amongst the wire bundle for the burnoff module. Correctly unplug the burnoff module plug, inspect for corrosion on both ends- I think 5 wire connections, use a little dialectic grease on each plug terminal and put back together - a bad connection in the burnoff module plug will throw a code 34. Remove neg battery cable before working on wiring and electronics --this will also clear all codes.

Restart and see what codes are given. There is more involved testing for a code 34 that is illustrated in other threads in this forum.

Buckeye88

Thanks! What area of Ohio? Go Bucks!

Cliff Harris

The '85 does not have external MAF relays. There is a MAF burnoff module, which does have a single relay that does both power and burnoff functions.

Here's the best error code listing I've found:

https://www.corvetteforum.com/forums...post1576116036

JrRifleCoach

Do not clean the MAF wire. If it is damaged you will have to replace it.
So before you consider this, price a replacement first.

Does the 85 have the EGR Switch on the r/h exhaust sample tube?
This was a major PITA for throwing a 34 code on my 86.

Good Luck







.