bad acceleration

deadcat · Post by **deadcat** » Tue Nov 30, 2004 1:30 pm

hey guys, sorry I haven't been on in a while,
work is a real pain at the moment.

just got a bit of a problem with the acceleration, when I put me foot down she shudders and amost stops, then goes racing off.

I'm sure I saw this before on here, but i can find it..

any help?

Karl_CLCoupe · Post by **Karl_CLCoupe** » Tue Nov 30, 2004 4:45 pm

I'm not too hot on this, but have you checked the throttle cable? No slack in there is there?

Just a thought. Sorry I couldn't be of more help!

Karl.

Gareth_GT_Hatch · Post by **Gareth_GT_Hatch** » Tue Nov 30, 2004 5:57 pm

Hmm Well the only time this happened to me I traced the source to a dodgy HT lead. Have you checked the ignition timing?

GroovyCarrot · Post by **GroovyCarrot** » Tue Nov 30, 2004 8:08 pm

I've just fixed exactly the same problem on mine, it was just running far, far too rich (like, flooding the cylinders with fuel every time I put my foot down, no wonder it was only putting out 33mpg..). Check your spark plugs, if they have a black coating on them, weaken your mixture (I assume this is adjustable on the mk3 throttle bodies and doesn't need electro-trickery with the ECU?) and it should improve no end...

Gareth_GT_Hatch · Post by **Gareth_GT_Hatch** » Tue Nov 30, 2004 10:20 pm

I dont think you can adjust that on a mk3 that sort of thing is governed by the lambda probe and ecu.

Tahrey1043 · Post by **Tahrey1043** » Tue Nov 30, 2004 11:07 pm

I G N I T I O N L E A D S

you knows it homeboy

er, well, at least, i THINK thats what was making mine bellyache in a similar manner before

if you have a tacho, is it kind of like there is bugger all below about 2500rpm, but after that its fairly normal? (i had that *really* wierd symptom - still dont know quite what it has to do with the leads, but changing them fixed it!)

GroovyCarrot · Post by **GroovyCarrot** » Tue Nov 30, 2004 11:16 pm

Shame, would have thought in a basic injection system they'd allow for a certain amount of manual adjustment... In that case I'd suggest checking the lambda probe etc, certainly check the plugs to see if it's overfuelling. My symptoms from having a very rich fuel mixture were poor economy and major flat spots (almost complete dead areas) around 1-2000 rpm, particularly noticable when I pulled away in 1st and 2nd gear where it would almost stall until either I floored it or it got over about 2,000 rpm. Spark plugs were absolutely covered in carbon, which has cleared up and been replaced with a grey-brown sort of colour now I've sorted it out a bit.

Gareth_GT_Hatch · Post by **Gareth_GT_Hatch** » Wed Dec 01, 2004 12:05 am

You can adjust the idle and CO content on a GT but thats about it. The single point injection engines arent adjustable at all as far as i know.

GroovyCarrot · Post by **GroovyCarrot** » Wed Dec 01, 2004 3:31 pm

Surely CO content is effectively just the mixture anyway?

LogIK · Post by **LogIK** » Wed Dec 01, 2004 4:39 pm

Aye, you are right Gaz. I have the booklet here on the Bosch Mono-Motronic SPI injection system, which is used on the MK3, and it is all self-regulating. Nothing can be adjusted, not even the idle point.

My spark plugs are carbon fouled, but there is nothing that I can adjust. It may be because I do a lot of short journeys, to and from work.

Tahrey1043 · Post by **Tahrey1043** » Wed Dec 01, 2004 8:47 pm

i reckon you could do some kind of adjusty by whacking a rheostat on the temp sensor...

dicking about with that has made mine idle down to 500 revs before and seems to richen the mix