12 replies to this topic

[Gary G]

Ok, for those that read my other thread titled 'cut out and now wont start' I have now managed to start it but the EML comes back on shortly after resetting the ECU and the revs fluctuate quite alot (sounds like i'm sitting there blipping the throttle) then it makes some funny noises before cutting out. I am now completely fed up with the car and have run out of ideas. I have replace the throttle body with a brand new item and found the cause to it not starting (or even turning over) was a 50amp fuse tucked away at the front! First time round getting it started i took it for a quick spin round the block (mile or so) without problem until arriving back and leaving it running then it sounded like it was running quieter then cut out and wouldnt fire but still turned over. After another reset and leaving it to idle for a minute I decided to take it out quickly again, this time i lost control of the throttle and it actually drove itself home which was interesting to say the least! I've checked nearly every electrical connection on the car (relays in boot, loom plugs side of expansion bottle, accelerator sensor connector, ECU connectors etc etc) all look fine but its current behaviour is leading me to believe either the acclerator pedal sensor is faulty or its the ECU? Does anyone have any ideas on this

[bigbadben]

may sound silly, but have you checked the sparkplugs? i've had a similar fault on another car that i traced to a sparkplug. The ceramic insulation had gone AWOL IIRC...

Edited by bigbadben, 16 September 2006 - 04:11 PM.

[Gary G]

Yeah I have mate- a couple of them had surface rust so I cleaned them and put them back. I think the problems electrical tbh as the car revs smooth when its being ok and doesnt control itself or cut out on me. Something is causing the EML and its either accelerator pedal sensor or the ECU's faulty i think. Think i'm just going to bite the bullit and trailor it to Thorney motorsport; hopefully they can have a look at it at and diagnose the actual problem. I actually wish it was monday now lol

[danuk]

as you know these cars dont have an idle controll valve. the idle is controlled by opening the throttle butterfly. you can either try cleaning the throttle body and breathers which is recommended anyway, just make sure you clean the throttle butterfly really well aswell. or as in your other post your throttle body is faulty. Another thing to check for are any airleaks. are all the breaher pipes and air intake pipe after the afm attatched propperly as that would also affect idle

[Gary G]

The throttle body on there now is brand new mate. Just had a quick look around and there doesnt seem to be any leaks. Cheers for the ideas so far mate.

[johnaachen]

The only other thing I can think of that you haven't tried is the lambda sensor - which controls the fuelling on the car. Check the connections of this - should be just downstream of engine out...before Pre-Cat. When you say lost complete control of the throttle that sounds like it went into limp home mode......but this should be able to be reset using a disgnostic tool eg Tech2 I reckon get someone to look at the lambda sensor......

[Gary G]

hmmm, makes sense as I have replaced the precat and back box.....was fairly carefull with the lamda's though. What about the EGR valve?? The car has covered less than 5k although its a 2001... could this valve be seized or something? Shall I try blanking it off and an ecu reset??

[johnaachen]

the egr valve....yeah maybe would explain the rough idle as egr should be active at idle.....if the egr valve is stuck in position it will generate a fault code Pxxxx....you need a tech 2 to check for this..... interestingly this is what i am doing at work at the moment....writing software that detects a sticking egr valve on a truck!!

[Gary G]

haha cool. Well I found this in the checking procedures: 'The behaviour of the engine at various different EGR rates may tell you if the EGR valve is working properly. Depending on the opening of the EGR Valve a certain amount of exhaust gas flows back into the intake system, enters the cylinders with the next opening of the intake valve, and is included in the next combustion cycle. If a high amount of exhaust gas is recirculated, the engine will not have enough oxygen for proper combustion (the o2 sensor recognisings lean combustion, injection time is increased). The engine will start to jerk. Recirculation rates of more than 15% will cause clearly noticeable engine jerk which will increase in proportion to the amout of recirculated exhaust gas. The engine will stall if the recirculation rate is greater than 75%' hmmm interesting

[Austin]

haha cool.

Well I found this in the checking procedures:

'The behaviour of the engine at various different EGR rates may tell you if the EGR valve is working properly. Depending on the opening of the EGR Valve a certain amount of exhaust gas flows back into the intake system, enters the cylinders with the next opening of the intake valve, and is included in the next combustion cycle. If a high amount of exhaust gas is recirculated, the engine will not have enough oxygen for proper combustion (the o2 sensor recognisings lean combustion, injection time is increased). The engine will start to jerk. Recirculation rates of more than 15% will cause clearly noticeable engine jerk which will increase in proportion to the amout of recirculated exhaust gas. The engine will stall if the recirculation rate is greater than 75%'

hmmm interesting

Gary,

Did you get a solution to this? I am having the same problem myself. Car is April 2001 with 32500 on it.

Had it in at Vauxhall dealer, they cleaned and tightened throttle body, but advised that it will need replaced shortly, at around £ 250. Also suggested a new EGR valve at about the same price.

Would be interested to know if you solved the problem.

Regards

Austin

[bigp2]

haha cool.

Well I found this in the checking procedures:

'The behaviour of the engine at various different EGR rates may tell you if the EGR valve is working properly. Depending on the opening of the EGR Valve a certain amount of exhaust gas flows back into the intake system, enters the cylinders with the next opening of the intake valve, and is included in the next combustion cycle. If a high amount of exhaust gas is recirculated, the engine will not have enough oxygen for proper combustion (the o2 sensor recognisings lean combustion, injection time is increased). The engine will start to jerk. Recirculation rates of more than 15% will cause clearly noticeable engine jerk which will increase in proportion to the amout of recirculated exhaust gas. The engine will stall if the recirculation rate is greater than 75%'

hmmm interesting

Gary,

Did you get a solution to this? I am having the same problem myself. Car is April 2001 with 32500 on it.

Had it in at Vauxhall dealer, they cleaned and tightened throttle body, but advised that it will need replaced shortly, at around £ 250. Also suggested a new EGR valve at about the same price.

Would be interested to know if you solved the problem.

Regards

Austin

I had a similar EGR valve problem (diagnosed by me disconnecting the EGR, and the problem went away). Got a new EGR on ebay for £70 and it couldn't be easier to replace.

Phil

[walkes]

Check the electric grounding near boot in engine bay. l14mha had this fault when he picked up his vxt. Simple 13mm spanner to tighten iirc job done

[Gary G]

The actual problem turned out to be the worst case scenario- the ecu. Thanks to vauxhall I also replaced the TB under their advice when it wasn't needed...oh well