89 Gt difficult starting (cold)
 

Hi Chaps, I am having issues starting my 89GT. To recap I had a idle issue AND a starting issue back in 2018 when I first bought the car. The starting issue turned out to be a broken king lead/coil connection. New leads all good, car then started great, first time, every time. Since 2018 the car has started well and idled well after about 2 mins of running so I have lived with it until now although I have bought a NOS ICV but not fitted yet.

However in the last couple of weeks I have been having terrible starting issues. When the key is turned it will fire but not catch and further starting achieves nothing other than flooding it. If I pull the FP relay XX and crank it, it will start and run, but then go very rich and run lumpy when I replace the relay. Once its running and "cleared" itself, it runs very well right up to WOT. I will be swapping the ICV but I don't think that's implicated in the starting problem, just idling. Where do I start in the troubleshooting - MAF, LH/EZK?

David
89Gt
86S2
88 944 Turbo S

Have you rebuilt the LH and MAF yet?

Also pull your vacuum lines off the FPR and dampers, if you smell or see fuel they have failed.

Is your tach bouncing when cranking. If not you could have a failed CPS.

Mine did the exact same thing. I would pull fuse 42(fuel pump,O2 sensor). Engine would then start and I just pushed fuse back in. Only happened when cold. My problem was a failing MAF.

If you want someone to check your MAF and ECUs I can do that, based in UK JDSPorsche and at least rule them out.

Temp II sensor? Mine behaved similarly (first start was fine, but if I shut off before it was warmed up it would need to sit for while and belched black when I got it started again).

Thanks Adamant, no the LH & MAF haven't been rebuilt, at least not in my ownership. Need to look back at the history to confirm provenance then maybe seen out for check/overhaul - EDIT, no they appear to be original

I checked the dampers and FPR, there is a slight smell but I can pull a vacuum on all of them and they hold

Re tach bounce, yes I think so as it does run

Thanks ZEUS

Interesting, I think the MAF is worth a closer look too.

Thanks Pagnobito, I think this may be on the cards. I will PM you

Thanks Tom, I think its original, so will test and report back

EDIT - measured the following at the LH & EZK;
- LH ground pin #17 to Temp II pin #13 = 2.397 kohms
- EZK ground pin #18 to Temp II pin #19 = 2.44 kohms
- both at approx 20degC ambient, against a spec of 1.4 to 3.6 kohms so in spec at that single temperature in both measurement cases and with ~1.8% variation side to side

For the present I am ruling out an issue with Temp II

I might not see it, better to make contact from my website. JDSPorsche

Mike

send out the MAF and the LH computer for rebuild ,
keep an eye on the dampers and FPR.
While the parts are out go charge the battery

It is not clear to me whether you are talking about cold starting or hot starting.

The temp2 values are fine for cold starting - I assume that is when you are having issues.

Hi Fred, yes cold start is the issue. Battery fully charged. I have been over the various grounds and cleaned them last year, but I think I will add these to the check list including the engine earth strap

Hi David,

Mike is excellent to deal with and doubtless he will turn your kit around test wise in no time should you elect to send the MAF and LH unit off to him and if the LH is original it might be worthwhile getting him to revamp it pre-emptively as it is not a question of if rather a question of when it goes tits up.

Considering the dialogue to date I cannot think of anything else that is obvious other than things like wiring harness issues

Please post a picture of the engine bay and the mileage, and if an intake refresh is ever been completed