Just helped a local TPI guy fix some problems on his LTR install. They installed the LTRs and had several problems after the install ...

Problem 1: Utilized '90-'92 LTRs on his '87 which meant that the IAC tube was totally plugged. Needless to say his idle sucked. We unplugged it.

Problem 2: Code 34 due to a major vacuum leak.
Solution: Nothing. We used carb cleaner and determined the Vacuum leak was coming from the cold start injector (thanx consultant Wayne!).

Anyhow - I figured the cheapest solution was to remove the cold start injector and upgrade to $6E code. Since I have never done this before, I have several questions...

1) Should I begin with the ARAP base code? Or can someone reference be to a better base code for a 1987 TPI Corvette with Automatic and 3.08's?
2) I notice that the EGR tube on the vette has some type of sensor on it that the F-Body does not. What the heck is this and is it run to the ECM? Will changing to the ARAP code affect the function of this sensor?
3) The vette has some type of trip computer that displays Miles per gallon and other stuff. When you pull the ECM fuse the trip computer resets. It is obviously controlled by the ECM or receives power via the ECM. Will the $6E code affect this?
4) The $6E has code for the Vehicle speed diagnostic. Do I need to disable this if he has a mechanical connection between the tranny and the speedometer (no VSS)?

Sorry for so many questions. I just want to help this guy out and save him some money. His only other options are either to buy a new cold start injector or to pay someone $200 to $300 for a 'custom' chip. I told him to hold off on that because I could do it for free for him and walk him through the process.

Tim

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TRAXION's 1990 IROC-Z
Best Time = 12.244 @ 112.51mph (1.778 60' / 7.819@88.32mph in the 1/8)
All Natural. No Force. No Drugs. Stock Bottom End. Stock Body Panels.
Gunning for NA 11's after installing Hooker LT Headers and reducing weight.
-=ICON Motorsports=-
Moderator: PROM board at thirdgen.org

 

I just did this code change 2 days ago. The car in question was an '87 Vette 4-spd auto with 3.07 gears and the cold start injector removed. I used the ARAP code and the car started without a hitch. Let me know if you need a copy of the stock ARAP bin.

Nick

 

Nick,

Yea, can you send me a copy of the BIN that you are running. I'll do a compare against the GM ARAP and find any differences. Thanx!

timsiford@hushmail.com

Tim

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TRAXION's 1990 IROC-Z
Best Time = 12.244 @ 112.51mph (1.778 60' / 7.819@88.32mph in the 1/8)
All Natural. No Force. No Drugs. Stock Bottom End. Stock Body Panels.
Gunning for NA 11's after installing Hooker LT Headers and reducing weight.
-=ICON Motorsports=-
Moderator: PROM board at thirdgen.org

 

The sensor on the EGR tube is probably a temp sensor to determine if the EGR sensor is working properly. On the '85-89 F-body EGR valves, this temp sensor is in the valve itself. Look at: http://www.fastlane.net/~thartman/egr.htm
to see what I'm referring to.

One question: why didn't he buy the correct-year LTR's to avoid this problem?

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Greg Westphal
'87 IROC 305TPI/A4

 

Greg,

He didn't know what he was doing Talk about a huge PITA. I posted on the MAFB list about it. It was a difficult job even for me. Greg ... can you answer any of my original questions? Just curious.

Tim

------------------
TRAXION's 1990 IROC-Z
Best Time = 12.244 @ 112.51mph (1.778 60' / 7.819@88.32mph in the 1/8)
All Natural. No Force. No Drugs. Stock Bottom End. Stock Body Panels.
Gunning for NA 11's after installing Hooker LT Headers and reducing weight.
-=ICON Motorsports=-
Moderator: PROM board at thirdgen.org

 

From what NickG says, it sounds like you can just start with the ARAP code and go from there. I mentioned in my previous reply that the sensor on the EGR tube is probably a diagnostic temp sensor. Don't know about Question #3, but I doubt it's a problem. Not sure about #4. The Code 34 is for the MAF, which usually means one of the MAF relays needs to be replaced. I had that problem a few years ago and I think I had to replace the power relay (the other one is the burn-off relay)...

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Greg Westphal
'87 IROC 305TPI/A4

 

Ahhh. Now I get it. Sometimes you have to tell me things twice. Question for you Greg. Your car has a mechanical speedo right? Did you disable the VSS diagnostic?

Tim

------------------
TRAXION's 1990 IROC-Z
Best Time = 12.244 @ 112.51mph (1.778 60' / 7.819@88.32mph in the 1/8)
All Natural. No Force. No Drugs. Stock Bottom End. Stock Body Panels.
Gunning for NA 11's after installing Hooker LT Headers and reducing weight.
-=ICON Motorsports=-
Moderator: PROM board at thirdgen.org

 

Yep, it has the mech. speedo. Just checked, and I still have the VSS diagnostic enabled. This is Veh. Speed Diag. in the ECM Switch Table right? I guess it's not hurting anything since everything's behaving normally on my car...

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Greg Westphal
'87 IROC 305TPI/A4

 

Thanks Greg. Hmmmm. I thought that the Vehicle Speed Diagnostic was for the VSS (non mechanical speedo). I guess it still could be. Hmmm. Thanks again.

Tim

------------------
TRAXION's 1990 IROC-Z
Best Time = 12.244 @ 112.51mph (1.778 60' / 7.819@88.32mph in the 1/8)
All Natural. No Force. No Drugs. Stock Bottom End. Stock Body Panels.
Gunning for NA 11's after installing Hooker LT Headers and reducing weight.
-=ICON Motorsports=-
Moderator: PROM board at thirdgen.org

 

Jagsthatrun have inline speedo adapters.
You really need it with an auto to get things right, and have a fIAC reset.
You cna get lost with a ecm getting a VSS some cars no to bad others are a disaster

You should have a ARAP in what I sent you.


ARAP was the GM chip used in all the magazine test cars, that tell ya anything?.