Author Topic: Hesitation/ misfire  (Read 2146 times)

tubbyG

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Hesitation/ misfire
« on: 17:38, Mon 20 September 2010 »
Ok, so had the 5 out for a bit today. While i was boosting in 2nd, it felt like one of the ht leads suddenly came off. I had a look and the leads were fine and all connected ok. When idleing it pops from the exhaust, and when driving it makes a really loud rumble, like a missfire and really hesitates on acceleration and has no power. Any ideas? Possible sooted up plugs?
Cheers

5teve L

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Re: Hesitation/ misfire
« Reply #1 on: 17:49, Mon 20 September 2010 »
Leads, plugs or cap is where I'd start.

tubbyG

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Re: Hesitation/ misfire
« Reply #2 on: 18:22, Mon 20 September 2010 »
Thats where my thoughts are too.. Just thought it was very strange,
Cheers on the speedy response tho;).

tubbyG

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Re: Hesitation/ misfire
« Reply #3 on: 22:56, Mon 20 September 2010 »
Got out of work at 9 and had a fumble wi my little duracell torch. All ht leads were fine, plugs seemed pretty clean, so i think the problem was the rubber seal on the mixture screw. When i took the screw out to check on it the seal was pretty warped, changed for a new one and All seems good again!.... For now;)

tubbyG

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Re: Hesitation/ misfire
« Reply #4 on: 10:50, Mon 27 September 2010 »
after running ok for a few days, it went back to being very lumpy, slow and loud. Had a carb in the garage which has had a rebuild so switched them over, put on new ht leads and plugs, but still the same....if not worse! :(  When tring to start it, it seems to stop itself, its like the engine turns and when its about to fire it feels like something stops it from turning more and the engine stops dead (wierd explanation but dont know what else to say!) so my thoughts are with timing. Feels like when a piston is about to ignite, there is something blocking it on the downstroke - maybe another piston.  Is it possible for timing to be knocked out while driving or idling?
got a guy popping over later tonight to have a look so hope its sorted soon

cheers

scratcher

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Re: Hesitation/ misfire
« Reply #5 on: 16:10, Mon 27 September 2010 »
I'd have a look at the dizzy cap like Steve said. I had the most minor crack in one before and it went how your's sounds.

tubbyG

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Re: Hesitation/ misfire
« Reply #6 on: 17:30, Mon 27 September 2010 »
Have checked dizzy cap, there is a small scratch on the outside but doesnt go right through, put on old cap and changed rotor arm but still the same:(. Mechanic lookin at it tonight so Will post up what he says after work

tubbyG

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Re: Hesitation/ misfire
« Reply #7 on: 23:26, Mon 27 September 2010 »
ok, so possible TDC sensor failure. Previous owner had it cable tied together with the king HT lead and vacum hoses so didnt really see much of it.  after inspection it looks like it has been VERY close to the turbo at one point and its impossible to disconnect the male/female connectors as they have melted together, will cut and rejoin so will see what happens.
Also when i got home, as I walked up the drive I could hear the fuel pump priming but the keys were out the ignition for 2 hours!!! had to disconnect the +tve terminal on battery to stop the whine so can someone tell me where the relay for the fuel pump is?

thanks

James5

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Re: Hesitation/ misfire
« Reply #8 on: 00:00, Tue 28 September 2010 »
Quote from: "Phase2-tungy-gtt"
ok, so possible TDC sensor failure. Previous owner had it cable tied together with the king HT lead and vacum hoses so didnt really see much of it.  after inspection it looks like it has been VERY close to the turbo at one point and its impossible to disconnect the male/female connectors as they have melted together, will cut and rejoin so will see what happens.
Also when i got home, as I walked up the drive I could hear the fuel pump priming but the keys were out the ignition for 2 hours!!! had to disconnect the +tve terminal on battery to stop the whine so can someone tell me where the relay for the fuel pump is?

thanks


Fuel Pump relay is under passenger side dash footwell, long black relay about 2" long by 1" wide

tubbyG

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Re: Hesitation/ misfire
« Reply #9 on: 00:15, Tue 28 September 2010 »
thanks james5  :wink:

tubbyG

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Re: Hesitation/ misfire
« Reply #10 on: 10:44, Wed 13 October 2010 »
car still wont start..............have changed fuel pump & relay, dizzy, HT leads, plugs, carb. but it still wont fire..
any other sugestions.....

cheers guys

James5

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Re: Hesitation/ misfire
« Reply #11 on: 12:08, Wed 13 October 2010 »
Quote from: "Phase2-tungy-gtt"
car still wont start..............have changed fuel pump & relay, dizzy, HT leads, plugs, carb. but it still wont fire..
any other sugestions.....

cheers guys


Ok is the starter motor cranking the engine?
are you getting spark?
Are you getting fuel to the carb?

tubbyG

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Re: Hesitation/ misfire
« Reply #12 on: 12:28, Wed 13 October 2010 »
Quote from: "James5"
Ok is the starter motor cranking the engine?
are you getting spark?
Are you getting fuel to the carb?

Yeah engine is turning over,
getting spark
fuel is ok - i think, will go to the car later and double check tho,

tubbyG

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Re: Hesitation/ misfire
« Reply #13 on: 18:45, Wed 13 October 2010 »
i've removed the carb top and can see fuel being squirted in. but i've noticed an oily substance inside the carb top and intercooler pipework. So while trying to start, if i pump the accelerator a few times it sounds like something wants to fire but a cloud of the black oily stuff comes shooting out the carb top!! WTF :x

James5

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Re: Hesitation/ misfire
« Reply #14 on: 12:14, Thu 14 October 2010 »
Are you running the standard breather system that feeds back into the turbo telephone hose?

Might be worth taking the carb off and giving it a decent clean to make sure no blockages, the same with the boost pipes and the intercooler.

To be honest if you have spark to all 4 leads and have fuel to the carb and the engine is cranking over then it should be starting.  Is the car even attemtping to start??

Has the car been run at all recently? has the timing on the dizzy actually been touched, are the HT leads in the correct order? are tappets correctly gapped?