Technical Tips > Electrical-Electronics-Air-Lighting-Guages-Security-Vacuum

87 Runs like a dog.

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Vettech:
 :grr: Have 87 - was running OK - now has a rolling miss, when pushed it farts and back fires - If didn't know better I'd say the "Timing' was out - disc the timing plug, T'Light on #1 and it shows ~6degs. This is about correct. But when the plug is disc - idle drops (but tacho says ~600rpm) and it runs even worserrrrr. Put on new leads, only codes I have are variable 33, 34 & 36 - ie air too low, too high and MAF burn off issue - these reset OK. I have little hair left but am at the hair pulling stage - I can't stand issues I can't diagnose from the books and symptoms
If this was an older style motor/ignition set up, I might say it was the vacumm advance but !?!?.
May have to change my handle. Any ideas greatly appreciated. Vettech.

69VETTE:

Hello Vettech,

I know if you haven't driven the car for a very long time, the analog computer,may if the battery hasnt been on a trickle charger go wonky, well not run spot on. .so when you start it up its all over the place and idling up an down and give you the symptoms you have described.

I had the same issues with mine when I purchased my car cause she hasn't been driven for over 7 months even with a trickle charger.

At the moment she's running beta but still occasionally runs odd. . only constant driving has sorted this out. 

Hopefully some other C4 owners can shed more light in this matter.

Vettech:
Thanks 69er - The car was idle for many years - but was rego-ed again in Dec '12 and has been on many club runs etc - and has been going very well. EXCEPT for the heating issue which I have not mentioned - maybe now will be a good time. Cold the car started and ran well, run for 30mins ++ and stop and try to restart within say 15mins and it sounded like either a flat battery or it was in the process of ceasing - but the actual water / oil temps were OK. Having said that it would always start after the second or third full rotation, BUT sometimes it would give a VERY LOUD "ping" so loud it really sounded like it had hit a valve - but once running it ran well no noises or issues - power to burn. I think I will remove the Starter motor and either rebuild or replace with a reduction drive style. Also renew the main cables, lugs etc  and fit a thin light weight S'Steel heat shield.
Regards. Vettech    any thoughts are very much appreciated.

Vettech:
OH! - something else on what you said - in a 87 and maybe all C4's the computer has what is called a "Block Learn" section in the memory - so if you wanted to go dragging - drive to the raceway disc the battery for 10-15mins - reconnect and then race it up and down the carpark or road as if dragging (6~8 times) this then tells the processor that you want that style of driving - and changes the Shift Hysteresis of the Box, the timing etc the result should be better times etc.
Sorry I digress.
Regards. Vettech.

69VETTE:
Your welcome. I was told by the previous owner that whilst the analog computers have there good points, they also a somewhat primitive. It sounds like your on the right track.

If you still have problems, contact Steve Rosenfeld at Rockdale as he is very knowledgeable on these units.

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