Miss fire, 4age redtop.

[shazeal]

Hiyas,

Im having a problem with my Redtop 4age. Basically once the car warms up it starts to miss fire. It happens at idle, or while cruising/accelerating. The plugs are only 4 months old. The plug leads are stock from new I think but check out ok with DMM. Timing was set 10deg BTDC a few weeks ago. Running 96 octane.

Only thing Ive done to the car lately was clean out the TB and install an oil catch can. I cleaned out the TB about a week ago and this started happening about 2 days ago. So im not convinced theyre related.

Anyone have any ideas as to what it might be?

Thanks.

[RickGT]

itll be ur tps, did it to mine too u need to reposition it

http://www.ae92gts.com/ae92gts_tps.html

[shazeal]

Excellent, sounds like it might be that from those symptoms. Ill give it a go.

[RickGT]

yea otherwise might be something to do with fuel or dizzy, the tps is very touchy so be patient

[shazeal]

Ok I had a go at setting this. All the readings come out fine except for the closed throttle one, it says should be 200-800, im getting 1100+ no matter where I set the TPS.

Could the TPS itself be faulty?

[shazeal]

Ok after much mucking about I found that if I pulled out a spark lead while the engine was at max heat, connected up the DMM the resistance read infinity on cylinder 4 spark lead.
From cold it measured normal.

Swapped all leads and problem seems to be gone.

[newby]

Ok after much mucking about I found that if I pulled out a spark lead while the engine was at max heat, connected up the DMM the resistance read infinity on cylinder 4 spark lead.
From cold it measured normal.

Swapped all leads and problem seems to be gone.

Hmmm, my redtop AE92 fxgt has a slight misfire too. It's got newish spark plugs - do you reckon it might be as simple as replacing the leads?

[shazeal]

Id measure the resistance on the leads first. You could have a fueling problem, only reason I looked so hard at my leads was the fact they were over 15 years old.
The next thing I was going to try was the Dizzy cap/rotor.

Basically my number 4 lead was giving a very high, but in spec reading for resistance when cold, and then a stupidly high to inifinite reading once the car had hotted up. Like 2.3 Mega Ohms.
The other leads where pretty much like number 4 all very high resistances ~20-25k Ohms, but still within manual specs.