Peugeot 205 GTi tuning woes.

[grahamthompson]

Having gone in circles for the past 6 weeks trying to track down a tuning problem with my previously bulletproof 205 GTi (1987), I am seeking new inspiration from forum readers. History as follows.
Car was running properly, as it has for the almost 8 years I have owned it, having never required tuning apart from plugs and timing belt. Recently I removed the inlet manifold to fix a starter problem (French Grr!). Apart from fuel lines, and injector wiring, accelerator cable, nothing was touched. On reassembly (new inlet manifold gasket) car refuses to idle, simply stops. Runs fine at 2000 revs and up, nice and clean. Idle screw is the tamperproof sort so problem is not that simple. On starting sounds like it has too much advance, so pull down distributor, find stuffed vacuum advance unit (which seems ancient but not previously affecting performance noticeably, and irrelevant to idling). Seems OK otherwise so check for jumped teeth on cambelt, also OK. Compressions are 135-155 psi, so are adequate.
Investigations are sidetracked by an intermittent problem in the tachymetric ignition control unit but Paul Lonergan's sharp eye found a critical bad connection in the relay so that particular problem seems now fixed.
Check throttle position switch which is one of those which registers only idle and full throttle position, find it is not registering at idle so hotwire it. No improvement. Remove tamperproof cap on idle screw and screw in, no improvement. Ditto air mixture screw. Find temperature sender for ECU dead so disconnect but I don't think that affects idle. On disconnecting air flow sensor, eureka, the car idles at 800 rpm but black smoke rich. Reconnect unit and engine stops instantly. A resistance check on the sensor shows some inconsistency, range 100 ohm increasing to 1400 ohm and back to 300 ohm at wide open. This compares to manual specs of 60 ohm to 1000 ohm but that doc does not define if this is gradual from closed to full open but I presume it means that. My sense is that readings are not far enough out of whack to be the cause of the problem. To add to my confusion on some (not all!!) of the most recent starts the engine leaps to 3000 odd rpm without having the throttle open at all. I have to shut it down in fright. And now it has run out of rego!!

Clues anyone?

[Paul M]

Graham,

Try another air flow meter (borrow, etc), they can cause a lot of issues when not operating correctly.

Also check the o2 sensor, it could be stuffed. (Once again borrow, etc to test).


Paul

[Saru]

It may be worth posting on AussieFrogs in the Peugeot section (if you haven't already) www.aussiefrogs.com

[grahamthompson]

Paul
Thanks for the response. If I knew of a convenient GTi I would have already done the swaps. I may have to flag one down locally. There is no O2 sensor, either visible or mentioned in workshop manual or wiring diagram.

Saru
Thanks for the contact for aussiefrogs. I may need their help

[tortfeaser]

Air temp sensor could be an issue as well as the MAF sensor. If left open circuit ECU may think its really cold and add fuel. If you suspect the MAF sensor (sounds not unreasonable) and there's no spare, go to Jaycar and bodge in a 1k potentiometer (variable resistor) set this to what the specs say the ECU should see at idle and test.

[GefGef]

Are you sure there are no air leaks anywhere in the intake after changing the manifold gasket? If not have you disconnected the battery when changing/fixing the starter motor? Might be a long shot but try cleaning the throttle body and idle bypass ports with carbyclean and disconnect battery again and see what happens.
I'd be willing to bet it's something relatively simple given the work done and not having a problem before hand.
Geoff

[grahamthompson]

Thank you all for input. Geoff and Steve Willett both helped me find the problem: a bloody air leak. The "supplementary air device" (French again) hose (cold start sysytem) which connects both out of sight and reach to the underside of the inlet manifold was leaking. I had to pull off the manifold again to locate it, and of course a manifold stud sheared when putting it back on so off it all came again. The 205 purrs again.