Lumpy running griff

[D14 ays]

Hi guys,

Had to pull the car out of the garage to get to a few bits and pieces, and couldn't resist the temptation to give the old girl an airing. I have noticed that when giving it some welly it seems to falter over the 4000RPM . It seems to backfire and pull back, this has only happened today. She starts fine, ticks over fine and runs fine, it's only when given some revs. Any advice would be most grateful before I go down the garage route. It's a 92 4.3 precat.
Thanks guys.

[nicbowman]

Give it a good run before you do much, roads were clean a nd dry today in Cambridge, though my 4.3 is still sat on axle stands waiting for the summer!

Nic

[tgriff]

coil amplifier
Steve

[D14 ays]

tgriff said:

coil amplifier
Steve

Please forgive my ignorance but whats that,were does it go,were do i get one,and how much, Thanks mate

[D14 ays]

[Roberto Rica]

Coil amplifier is a little flat black box, on side of distributor on early cars, up near the coil on later cars - costs about 60 quid.

Tim at ACT does them.

Rob

[D14 ays]

Hi guys,
I went to Tims of ACT yesterday to pick a few parts up for my sick griff,this morning i put on the new parts consisting of,

1 Coil amplifier
2 Magnicor leads
3 Bosch coil
4 Rotor arm
5 Dizzy cap
6 Sparkplug extenders

removed plugs and cleaned they are only 500 miles old anyway,on the test drive the car went like a dream for 15 mins them on giving some beans to the old girl back fires and pulling back again,were do i look now At this rate in about 6 months my car will be brand new Thanks in advance for any advice.

[Roberto Rica]

Air Flow Meter - get your multimeter out.
How much were the distributor cap and rotor arm?

Rob

[griffsmith]

D14 ays said:

Hi guys,
I went to Tims of ACT yesterday to pick a few parts up for my sick griff,this morning i put on the new parts consisting of,

1 Coil amplifier
2 Magnicor leads
3 Bosch coil
4 Rotor arm
5 Dizzy cap
6 Sparkplug extenders

removed plugs and cleaned they are only 500 miles old anyway,on the test drive the car went like a dream for 15 mins them on giving some beans to the old girl back fires and pulling back again,were do i look now At this rate in about 6 months my car will be brand new Thanks in advance for any advice.

Have you reset the ECU? (disconnect the battery for a 30-60 secs). the car could have put itself into 'limp home' mode which means it runs bloody rich and gives the symptoms you mention. once you reconnect re-testdrive in the sun and all will be fine I hope

PS nothing wrong with a brand new Pre-Cat that would be the best TVR of all!! that's if it's not already

Edited by griffsmith on Thursday 1st March 20:14

[D14 ays]

Roberto Rica said:

Air Flow Meter - get your multimeter out.
How much were the distributor cap and rotor arm?

Rob

Hi Rob,

Lucas rotor arm £9.50 + VAT (Tim described it as rare as hen's teeth.)

Dizzy Cap £17.00 + VAT

I will get my multimeter out and try your suggestion.

Thanks Rob

[Roberto Rica]

Thanks

I agree with Griffsmith before doing anything drastic reset your ECU.

Rob

[barreti]

Could it be something awry with the induction?
Have you tried running it without the air filter attached.
Could you remove the induction pipe from the AFM and take it for a whiz to discount it as the cause?
Might be a bit of a daft suggestion but thats never stopped me in the past so why start now

[spend]

It sounds like you have renewed your ignition ~ has the timing been checked (did your AA man play with it during the rotor arm incident)?

Dave

[davetherave1970]

I think the air flow meter starts reading after the temp get above 50 or 60. This would make sense if your test drive started out ok then later ran into problems!
Just a thought.

[spend]

Ballistic Banana said:

Another one to throw into the pot is that 4k or 3k rpm isnt it around 3k the lambas kick in, if thast firked then that could be the prob.

Wouldnt that indicate an incorrect tune resistor (precat)?

Dave

[Ballistic Banana]

spend said:

Ballistic Banana said:

Another one to throw into the pot is that 4k or 3k rpm isnt it around 3k the lambas kick in, if thast firked then that could be the prob.

Wouldnt that indicate an incorrect tune resistor (precat)?

Dave

where did you get that quote from Dave !!


BB

No your right, I forgot its a 4.3

[spend]

You may well be right, it quite possibly has an identity crisis Simon The way you Griff boyos shuffle parts around ~ who knows what ecu it is hiding in its footwell! You were spot on to say to check it, I reckon a quick scan of the ecu label & verify the tune resistor attached is correct would be reassuring. I just had the impression that the real precats were not as susceptible to a lot of the fuelling probs the rest of us can suffer?

Dave

dont tell LG but I loaned my bible to somebody, so cant lookup the tune resistor

[D14 ays]

spend said:

It sounds like you have renewed your ignition ~ has the timing been checked (did your AA man play with it during the rotor arm incident)?

Dave

Hi Dave, The AA man quickly found the problem with the rotor arm with out to much messing about,but i will get it checked anyway,
Thanks
Dean

[jeffsy]

Are you sure that you havent filled it with petrol from any leading supermarkets?

[griffsmith]

jeffsy said:

Are you sure that you havent filled it with petrol from any leading supermarkets?

Another great reason to have a pre-cat no lambdas to knacker with all this duff fuel floating about

D14ays - start with the obvious! if the AFM / induction system / tune resistor were alright prior to your ignition problem the chances are they are still ok.

The only other thing is that whilst you were changing all that you disturbed other sleeping gremlins, like crispy wires

The trouble with measuring AFM readings is that everyone I've spoken to, gets different readings and the cars still run fine. if anyone comes up with definitive AFM readings (bearing in mind this is a pre-cat probably with a 3AM meter) let me know I've got loads of readings from mine to compare..

Try the ECU rest and good test drive to get it back to normal..

Edited by griffsmith on Friday 2nd March 09:58