Missfire - please help before I scrap it!

Post Wed Nov 08, 2006 8:28 pm

Right not in the slightest bit happy at the moment!

Just taken the car out for a spin, and the ruddy missfire is back.

When I first started it (first time in about 5 days) it was quite lumpy, settled to a steady idle. first few miles were taken easily as the engine was still warming. after approx 5-6 miles, I opened up to 3/4 throttle and it was a little hesitant but not really missing.

Upon full throttle and at around 5k, it feels almost like its on the limiter, just nothing. I can get it above 5k by slowly bringing it up through the revs.

About 2 months ago I replaced the distributor cap and rotor arm as this was the main suspect for the miss,
plugs are no more than 4 months old,
leads have no obvious signs of damage.
New brown sensor a couple of weeks ago,
blue sensor still to fit but have here.

What the hell could be wrong?

This is getting seriously frustrating. Please help me guys.

Post Wed Nov 08, 2006 8:48 pm

Fuel consumption changed Dave ??

Check all the obviou air leaks etc.

Check the resistance @ the crank sensor, 330 ohms, the plug is under the diagnostic socket.

cheak you are actually getting WOT too, its a common E30/34 complaint , check the cable will open the TB to the stop, and ajust as required.

check also the operation of the TPS

A lot of people would blame the AFM, but thats "ignored" by the ECU over 4.7-5K @ full load ( WOT) only provied the TPS sends that signal.

Multimeter time Dave.

HTH- let us know what you find

Post Wed Nov 08, 2006 8:54 pm

Oh don't say multimeter Ant, I have no idea how to use one

Fuel consumption fine, Got about 115 miles to a third of a tank so actually pretty good!

Just had a new throttle body boot as the other had a small split, tried the wd40 around the inlet manifold trick to check for leaks, all seems ok.

TPS should click when throttle opened right? iirc it does.

WOT checked by pushing pedal to floor and checking there is no more movement in the butterfly?

Thanks for your help dude. I'm stressing my fat ass off here

Post Wed Nov 08, 2006 8:57 pm

d6dph wrote: Fuel consumption fine, Got about 115 miles to a third of a tank so actually pretty good!

Post Wed Nov 08, 2006 9:02 pm

Is for my driving, Spirited is a good phrase.

Post Wed Nov 08, 2006 9:08 pm

Timing senser? located on the o/s/f of the block next to the timing wheel on the front of the crank, sometimes the mount fails??

Post Wed Nov 08, 2006 9:08 pm

Ãƒ”šÃ‚£20 = 100 miles in Betty

Post Wed Nov 08, 2006 10:02 pm

Right, just been for a fiddle...... Then went out to the car.

Neil, The sensor looks fine and the bracket is sturdy so I dont think it is that. Plugs all look ok, so i guess its out with the multimeter tomorrow night.

This is going to sound really stupid, but you all know what I'm like by now!, Where is the diagnostic socket? Is it the large plug next to the inlet manifold and dipstick (the one on the car, not me!)?

If so, there is two plugs below it, which one is the crank position plug?

Thanks again guys,

Shall we start the bidding at 50p? Come on she's not a bad old car, got to be worth 50p!

Post Wed Nov 08, 2006 10:32 pm

I'll buy the strut brace back Dave, if you leave it attached to the car

Good luck dude as I sure as hell don't know what to do with a multimeter

Post Wed Nov 08, 2006 10:39 pm

have a look at engine running in dark,may see ht jumping/tracking,all the same ,check plugs ,cap,arm again...

Post Wed Nov 08, 2006 11:01 pm

You need to check the TPS is actually switching, by testing it with a meter. One pair of contacts switch just off idle, the other pair switch at about 2/3 throttle.

Post Thu Nov 09, 2006 9:11 pm

Well i will still check all the things mentioned above, but drove it this evening and it was perfect? Very odd

What's the chances of it being something daft like condensation in the dizzy cap or the likes?

Post Thu Nov 09, 2006 9:34 pm

there can be alot of oil crap around the TPS, un plug it and see if it's all kacked up mate. It could just need a clean on the contacts

Post Thu Nov 09, 2006 9:38 pm

Cool, Cheers Si, I have quite a list to do on saturday!

Oh and Lee, Auction for my car is off, put that shiney pound coin away

Post Thu Nov 09, 2006 9:51 pm

d6dph wrote:Well i will still check all the things mentioned above, but drove it this evening and it was perfect? Very odd

What's the chances of it being something daft like condensation in the dizzy cap or the likes?

every chance as i said above.......