help - turbo misfiring

diabloam · Nov 3, 2008

Any suggestions guys. Was away couple of weeks and on return car started fine but seemed to run rough. Anyway thought it would clear with a wee blast but it died few yards up the road. Went to get mate to tow back to house but tried it one last time, after taping relays and stuff and it started!. Still running rough and as soon as i gave it some throttle it would start to splutter and miss (basically as soon as boost gauge showed positive). Anyway drove it gently about till it warmed up and it cleared and seemed back to normal, pullling like it should. Went to it today and started first turn, but been spluttering and missing with pretty much any throttle or boost, but if I just toddle its fine. Been looking for leaks in vacuum pipes etc and round boost enhancer but cant see anything amiss, also checked 951 FAQ's but cant see anything relevent. So not sure what to look at, fueling? DME relay? or ignition stuff, or is it the turbo and associated gubbin's causing this. Anybody had similar problem?

It did this on me a few months back but seemed to sort itself, so think it must be something intermittant! Anyway as always the forums knowledge is greatly appreciated, thanks all who post and help, cheers

diabloam · Nov 4, 2008

hey all - any suggestions welcomed as going to have look at car tonight, cheers

sawood12 · Nov 4, 2008

How old are your HT leads, dizzy cap and rotor arm? I replaced mine pro-actively but was pretty shocked at the state of them. Surprised they were working at all.

homesea · Nov 4, 2008

Start with the basics like Scott said, but a cut out then no start sounds like DME relay. But saying that it has nothing to do with a misfire or when the car comes on boost. The only other thing I can think of is the TPS but dont know why that would stop it from starting. Easy to test, just unplug it and see how it runs.

marty · Nov 4, 2008

I had this problem a while ago and it was very intermittant, maybe two or three times in six months, then I had the car on a rolling road and was told it was running very rich. I decided I had better have it looked at by a specialist so I took it to Promax for a full check over. After some initial puzzling it turned out to be the Air Flow Meter that was causing the problem. An exchange item was fitted and the car has been running perfectly ever since.
Of course lots of other things can cause the same problem.
Intermittant faults are a pain.

diabloam · Nov 4, 2008

well i checked for vacuum leaks, backed off the boost enhancer 2 turns( 2psi) (think this was set too high anyway) and reclipped the top screw on distributer cap (it seemed little loose, so pushed it in a little and turned/played with top screw were it seemed loose, according to clarke-garage instuctions on taking cap on/off).

It started first time and idled like normal, so went for a drive, car missing when picking up, but didnt boot it totally till it warmed up. Anyway it seemed to clear when warmer and at small throttle openings and no boost car is fine, but when going into boost ( above 1.2 on factory gauge) it starts to splutter and miss. Pulls great off boost and picking up to atmospheric pressure like normal, i.e quick 1000rpm to 2500 rpm (bottom factory gauge to about 1.2bar) like normal, even at full throttle opening it pulls low down fine, but it starts to miss as soon as get little bit of positive boost. But if you keep booting it will eventually splutter all the way to produce the boost but the splutters never goes away all the way up. Could it really be ht leads and cap and arm, or look elsewhere. If I keep it booted it will produce a 1.75-1.8 bar on factory gauge, about 10-12 psi on my aftermarket gauge, weird!, must be something fairly simple I hope and certainly doesnt seem it is anything terminal, has to be a faulty component or something. Sorry for long post but thought it best to be indepth to help everybody diagnose this. Thanks for all help guys!

diabloam · Nov 7, 2008

sorted I think, top clip on distrib cap didnt seem to be locked in, cap a little out, so played with that till it seemed better and car was fine all day, thanks everybody who helped us, much appreciated. Might still get new leads, cap and rotor arm as they look original (1986)