jimma4191

For some reason the previous owner of my 1985 vette put in a 1986 top end. We've had a heck of a time trying to get it running right. Turned out every hand under the hood kept installing a 1985 EGR. Wrong. She's running much better now with the 86 EGR but still not great. What other parts will be affected by this set up?
Thanks
Jim
Maybe this was a dumb question. Maybe a tricky one. I only know enough to get myself in trouble. Will the distributor conflict with the 86 top end? The spark control module? The ECM? What about the MAF, is that now the wrong maf sensor? Will this never be right? Should I look to replace the top with an 85? Should I send the car to the junk yard?

powerpigz-51

You need to be more specific about what your problems are.....I am assuming it has iron heads? If it does, going from 85 to 86 should not be a problem. Codes? What is it doing?

jimma4191

Thank you for the reply. I was getting 32 and 43 before installing the appropriate egr. It ran fine initially with no codes and advancing nicely when accelerating. Now just today it starts with no code until I drive off I lose power, a little backfire and I'm getting 32 and 33. Never saw 33 before. It will also start searching after sitting at idle for a few minutes. I can even that out by playing with the iac but then it returns after it sits for a bit.

Jim

jimma4191

Just out for a quick ride and now got 24,32,33 and 43. Anybody got a match

tunedport85inject

24= vehicle speed sensor
32= egr system failure
33= MAF voltage high
43= electronic spark control ESC

jimma4191

New maf, new 86 egr, new spark control module in new distributor. New throttle body. Recent wires, plugs and injectors. ECM tested ok. Let's see what else....

tunedport85inject

talking about spark control module or ignition module in new distributor?

ESC module


ignition module

jimma4191

we replaced the module in the distributor. I think he eliminated a problem with this one in the picture. Where is that located?
Thanks

tunedport85inject

ignition module even if new has nothing to do with code 43,that's for Electronic spark control module ESC: this device works with the knock sensor on the block if a knock is detected this device retard the timing electronically to prevent detonation damnage to the engine.This device is also cecked once per start by the ecm simulating a knock (by advancing the timing with coolant temp above 90° C at WOT)if the functional ceck fails ecm sets a code 43.Device is located engine bay,passenger side over windshield washer tank

coupeguy2001

ESC is year specific. get one for an 86. If you have an 86 top end, you probably have an 86 computer as well as an 86 wire harness.
Is there a EGR solenoid bolted to the water outlet? If so, you have and 86 car for all intents and purposes. Buy everything for an 86 and forget the vin says 85.

Now there is the sensors. alll should be out of an 86 car. This means you do not have a maf module anymore. tread lightly here, the MAF might be an 85, it needs to be an 86-89

Cliff Harris

You will get an error code 33 under two conditions:

1 - MAF is bad

2 - Bad connection between the MAF and the ECM. That could be a corroded pin in a connector, broken wire or unplugged MAF.

LongBeachC4

I was told be J&D that 86 heads might cause a problem with the knock sensor. Not sure why, I was looking at buying a good used set of 86 heads for my 85 when I get ready to do a full refit.

vader86

I don't see why. Same head casting for the iron. I don't readily see why the Aluminum later-86 128 casting would cause a knock problem because CR didn't really change much. Would still run on 87 octane.

jimma4191

Off to buy an 86 esc. Maf said 85 thru 89. Is that ng? I will check connections. I've been throwing money at this car for three years. Never saw 33 before. Things have changed with the 86 EGR for sure.

jimma4191

ESC like the MAF says 84,85 and 86

tunedport85inject

i agree, ecklers says 84 thru 86 for the ESC module

http://www.ecklerscorvette.com/corve...1984-1986.html

before throwing parts again on the car i will ceck ESC system by FSM procedure:this is from my 85 FSM
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jimma4191

The spark control module is new. I have tried to avoid sounding like a rookie but here goes. She starts with no SES. All's well. It runs better and the searching is better with the new EGR. Cruising at 30mph or 50mph, if you lightly accelerate she starts lugging, pings and gives a SES light. If you jump on it she'll advance and no problem. At those speeds it's like she's in the wrong gear. I'm getting 24, 32 and 43. I'm really surprised to see the EGR code. Could it be the temp sensor? It is running better with the 86 EGR. It must be a sensor problem or could it be the tranny? We've been trying to solve this for 3 years now. With the EGR turning point we can only wonder what else is in play here.

AGENT 86

Yes, there is a problem with the EGR temp switch or circuit.

From my 86 FSM

http://members.shaw.ca/corvette86/Code%2024.pdf

http://members.shaw.ca/corvette86/Code%2032.pdf

http://members.shaw.ca/corvette86/Code%2043.pdf

Here is a vacuum diagram for 86



Is it still 85 ECM ?

jimma4191

I have ordered a new EGR temp sensor. There was a 1986 year specific sensor installed with the 86 top end but I have a feeling it was defective. My mechanic has gone through the vacuum system and I am very confident in him. And the vacuum schematic is under the hood. I have high hopes. Could the code 24 have come up from the new throttle body in any way? That really seemed to come from nowhere. Thank you and I'll let you know come Monday. I can't wait!!

klkordzi

I have an 85 and replaced the top end with one from an 86. I used aluminum heads, eliminated the EGR, added a bigger cam, headers,1.6 rockers, Bosch injectors. It has never thrown a code. The 85 computer is very forgiving of changes to the engine so I would not assume your problems are related to the swapping of parts.