Problem With Running From Cold

[Big_Jimbob 0]

Hey guys, iv been having this problem for about a week now, when i start the car it fires up fine,

 

but then for the first 15-20 seconds seems to run on 3 cylinders or just very weak when held at 2000 revs.

 

the problem then goes away and another arrises, it sounds smooth enough and ticks over at about 1000 revs,

but as soon as i try and draw off and put the engine under load it back fires and stutters and tries to cut out...

 

If i sit and let the car reach full temp then try again it is fine, no miss fires no back fires....

 

Iv replaced

 

ignition amp with a known good one

Plugs

Leads

Dissy cap

Rotor arm

cleaned the coil terminals

 

does anybody have any ideas what the problem could be or how to find out?

 

thanks

Jim

[Pugnut 9 1 Cars]

i would be checking the ecu engine temp sensor. its the one the therrmostat housing that has the multipin style of connector .

[Big_Jimbob 0]

I replaced the ecu temp sensor about a yr and a half ago, but i will run some tests on it tomorrow..... (could eaisly be that as the fuel consumption is up too.....)

 

would it also be a good idea to remove the sad and test/clean that?

 

thanks

Jim

[Pugnut 9 1 Cars]

would it also be a good idea to remove the sad and test/clean that?

 

thanks

Jim

 

if the sad were at fault you would easily be able to compensate for the lack of air by giving a bit of extra throttle. you wouldn't experience any backfiring etc.

 

so the car run perfectly fine when its warm??

[Big_Jimbob 0]

Yep, its spot on when its warm..... if i sit with the car ticking over until it reaches half on the gauge it will pull off fine....

 

im also gonna try and get a new coil as its the only thing i havent replaced....

 

it just seams strange that it only does it when its cold....

 

Jim

[DamirGTI 344]

Hi !

 

Odd I'd say injectors or AFM maybe but if it's fine when the engine warms up that doesn't make sense then does it ?!.. try with some spare coil then if you didn't try yet :

a few words from coil testing guide

"...a coil, like any other metal component, expands with heat and the windings may be making contact when the coil is expanded but not when cold, or vice versa."

 

 

and full text if you wish to read trough :

http://www.castensdynojet.com/ignitioncoils.htm

 

Cheers !

Damir

[Big_Jimbob 0]

could it be an injector seal, leaking when cold and hard but when it warms up expands and seals the injector?

 

just spitballing.....

 

Jim

[DamirGTI 344]

i really don' know , but I've had "similar" problem however my engine was running on 3 cylinders all the time hot or cold no matter and it was one injector which was burnt out after ultrasonic cleaning (was working fine 6hours after cleaning and then next day in the morning started with 3 cylinder game , anyway I've fit another spare injector and fix that ..)

 

Did you check the signal wire which goes from the dizzy to the ignition amp. with multimeter ? ignition amp. connector ?

 

Damir

 

EDIT : are you sure that you didn't fried up (by mistake maybe when you've been fitting him ?!) this spare ignition amp. ?

Edited January 1, 2008 by DamirGTI

[Big_Jimbob 0]

they all looked alright, but i didnt test them...

 

how should i test them?

 

Jim

[Big_Jimbob 0]

sorry mate i dont get what you mean in your edit.....

[DamirGTI 344]

...i mean when you've been replacing the ignition amp. with another one , maybe you burnt that spare amp. by twisting some wires while moving the amp. plate around or something like that did you re-apply the thermal transfer paste at the back of the amp. when you've been changing him ?

 

as for the dizzy signal cable - check the wires for continuity with multimeter , theres 2 wires inside the cable (black and red) well 3 but one is just a shielding wire , the one without insulation ... unplug the yellow connector in the middle , remove the dizzy cap and look inside the dizzy beneath the rotor arm/shaft you'll see two wires plugged on the pick up coil - pick one multimeter probe in one wire/contact inside the dizzy and slide another probe on the terminals at the end of the yellow cable plug until you hear/find the signal and do the same with the second wire ... while doing that , when you hear/find the signal for each wire hold the multimeter probes still connected and try to swing the cable up and down left and right and listen if the sound of the multimeter buzzer will change/break down at some point when you twist the cable ...

 

(adjust the multimeter on the buzzer for testing this !)

 

Damir

Edited January 1, 2008 by DamirGTI

[Big_Jimbob 0]

Ah i get you know mate, i didnt put any thermal transfer paste on the amp as i thought the metal backing was to earth the thing......

 

where would i get some from?

 

by the yellow plug, do you mean the one that connects the dissy to the amp... if so im sure mine is black ("f" reg car)

 

I will test all these today and report back....

 

Thanks for your help guys...

 

Jim

[TVH 0]

Ah i get you know mate, i didnt put any thermal transfer paste on the amp as i thought the metal backing was to earth the thing......

 

where would i get some from?

 

by the yellow plug, do you mean the one that connects the dissy to the amp... if so im sure mine is black ("f" reg car)

 

I will test all these today and report back....

 

Thanks for your help guys...

 

Jim

 

Did you already check the ecu temp sensor?

[DamirGTI 344]

Ah i get you know mate, i didnt put any thermal transfer paste on the amp as i thought the metal backing was to earth the thing......

 

where would i get some from?

 

by the yellow plug, do you mean the one that connects the dissy to the amp... if so im sure mine is black ("f" reg car)

 

I will test all these today and report back....

 

Thanks for your help guys...

 

Jim

 

Hi !

 

Whenever you change the ignition amp. you must re-apply the thermal transfer paste/heat soak jelly ... as this protects the amp. from overheating (when the amp. overheats - it fails) and if you don't do that you can parch the amp. (new one or a spare one no matter ..) in just a few hours !!

 

You can buy this paste/jelly in computer store , any type of heat soak paste/jelly will do just fine no need for something special like - "heat soak paste just for car ignition components" ... ask for : silicone heat transfer compound

 

Yes thats the one - cable which goes from the dizzy with 3-pin plug on the end (this cable connects dizzy with ignition amp/coil)

 

Best luck !

Damir

Edited January 2, 2008 by DamirGTI

[simonb 0]

If the amp was fried then I doubt that the car would run at all and you would have problems all through the rev range when hot. Your cold start missing sounds like a fueling or ignition problem to me and could possibly be a weak spark on one cylinder when cold caused by the coil perhaps .

 

If you have changed the ECU temp sensor and all is still not well, make sure that the connector is OK and try starting the car with it unplugged - is there any difference? i.e. is it worse? if it's the same then your problem lies here. Another trick would be to temporarily tighten the AFM spring about 5-6 teeth before starting and seeing if this helps the initial startup. If it does - then this too would point to overfueling on initial startup.

 

You could also whip the plugs out before starting and make sure they are not wet as this could cause the problem you describe.

 

Just a few ideas - hope this helps.

[Big_Jimbob 0]

I think i have sorted this problem now......

 

iv checked the wiring and all is well (cleaned the connections too)

 

tested the ecu temp sensor and its roughly correct, tested the dissy wiring and all is ok...

 

I changed the dissy cap and rotor to the old one to see if these were at fault,

 

i left the car for 2.5 hrs and it fired up well and ran well....with this one it pulls from cold but still only fired on 3 cylinders for the first 20 seconds..... is this common?

 

 

im presuming that the cap or rotor arm is faulty...

 

thanks guys for all your help, i will be able to tell u for sure if this is the problem sorted tomorrow morning....

[simonb 0]

I bet that it will still be a problem - I don't think that 2.5 hrs won't be long enough for whatever is happening to settle down as the engine will not be as stone cold as it is if left overnight...

[Big_Jimbob 0]

Problem sorted now, turned out to be a faulty dissy cap and/or rotor arm.......

 

iv changed it back to the origional ones and she runs fine.....

 

 

i am still having the initial start up problem of it sounding like its either running on 3 cylinders or running weak when revved....

It will still however still tick over, it only sounds bad when you bring the revs up between 2k and 3k....

 

is this normal?

 

Jim

[simonb 0]

Try some of the things I mentioned above - initial Fueling - spark - water on plugs etc...

 

Pretty sure it's not normal. How about your cam timing? If this is a bit out, it can cause a lumpy idle.