Rough idle on startup - 986 Forum - The Community for Porsche Boxster & Cayman Owners

marin3e · 01-29-2017, 01:43 AM

Hi guys, I have a 98 2.5 boxster, it is hard to start first thing, it coughs and misfires and takes me approx 4 starts to get it started. Once it has started its fine, and it will start perfectly for the rest of the day first go.

I have replaced the plugs,
I took the MAF sensor off and gave it a spray with MAF cleaner,

Just wondering if anyone could give me a heads up.
Cheers
Brett
:dance:

Gelbster · 01-30-2017, 03:58 PM

Speculating but without an error code ,it is difficult to do better- have you tried testing the CPS ? Search for the resistance spec.Easy to do.Can you use a code reader to tell us the codes? Better still find someone with a Durametric cable?
Then there is all the routine maintenance items that may be O.K. but sometimes the poking around reveals a problem - TB cleaning,Vac leaks, plugs etc.

911monty · 01-30-2017, 05:01 PM

Have you cleaned the TB, specifically the IACV? The IACV controls the idle air on startup and could be gummed up. My TB was fairly clean but the IACV had quite a bit of crap in it.Easy DIY. You will need a TB O ring and an IACV gasket.

marin3e · 01-31-2017, 02:33 AM

Thanks fella's, Ive got a OBD2 scanner, not sure if it will read the Boxster but will give it a go. TB is a good place to start.
really appreciate your input

Brett

marin3e · 01-31-2017, 02:36 AM

Will also investigate the Idle air control valve as suggested =) cheers

Gelbster · 02-03-2017, 01:16 PM

Quote:

Originally Posted by marin3e

Hi guys, I have a 98 2.5 boxster, it is hard to start first thing, it coughs and misfires and takes me approx 4 starts to get it started. Once it has started its fine, and it will start perfectly for the rest of the day first go.

I have replaced the plugs,
I took the MAF sensor off and gave it a spray with MAF cleaner,

Just wondering if anyone could give me a heads up.
Cheers
Brett
:dance:

What happens if you let the starter motor run a little longer? I ask because I am wondering if a leaky injector(s) is causing a slow build in adequate fuel pressure.It may be useful to monitor fuel pressure from a cold start.Suggest you Search for the specs and how/where to attach the fuel pressure tester if you think this is possibility.On an older car with lots of miles on the injectors it is plausible speculation.