172 cup wont rev over 3k once hot

[jamiemonk567]

Been having an issue recently where car runs fine for around 30mins then all of a sudden wont rev past 3k and it becomes very jolty and the engine sounds like its stopping and popping runs fine below 3k no misfires. No fault codes either unsure where to start

Any help would be great thanks

 

[Martin_172]

Would need to plug it in and look at live data.

Off the top of my head id be looking at:
White plug under the fuse box for corrosion.
Relays in the fuse box for corrosion
Check injectors
Replacement throttle body
Replacement accelerator pedal

 

[jamiemonk567]

Would need to plug it in and look at live data.

Off the top of my head id be looking at:
White plug under the fuse box for corrosion.
Relays in the fuse box for corrosion
Check injectors
Replacement throttle body
Replacement accelerator pedal

On my cheap ish obd scanner my throttle position was around 4% closed and full throttle reading around 65% wondered if maybe the pedal sensor was on its way out
Will have a look at those this morning any idea where to buy pedal and body new if possible

Cheers for the quick reply

 

[Martin_172]

On my cheap ish obd scanner my throttle position was around 4% closed and full throttle reading around 65% wondered if maybe the pedal sensor was on its way out
Will have a look at those this morning any idea where to buy pedal and body new if possible

Cheers for the quick reply

To be honest the pedal and TB are expensive. I would chance my luck with a 2nd hand one first as it's not a massively common fault so you would be unlucky to end up with another faulty one.


HOWEVER that white plug under the fuse box sends so many people down the throttle body and pedal route when it's not.

Get some electrical contact cleaner, give it a proper good spray. Connect it and disconnect it a load of times, spray again and repeat etc to clean it up and then stick it back together.

If you remove the engine bay fuse box cover, clip the relay panel out you will see the connector in the bottom of the fuse box

 

[jamiemonk567]

To be honest the pedal and TB are expensive. I would chance my luck with a 2nd hand one first as it's not a massively common fault so you would be unlucky to end up with another faulty one.


HOWEVER that white plug under the fuse box sends so many people down the throttle body and pedal route when it's not.

Get some electrical contact cleaner, give it a proper good spray. Connect it and disconnect it a load of times, spray again and repeat etc to clean it up and then stick it back together.

If you remove the engine bay fuse box cover, clip the relay panel out you will see the connector in the bottom of the fuse box

Thanks will give it a go 👍

 

[jamiemonk567]

To be honest the pedal and TB are expensive. I would chance my luck with a 2nd hand one first as it's not a massively common fault so you would be unlucky to end up with another faulty one.


HOWEVER that white plug under the fuse box sends so many people down the throttle body and pedal route when it's not.

Get some electrical contact cleaner, give it a proper good spray. Connect it and disconnect it a load of times, spray again and repeat etc to clean it up and then stick it back together.

If you remove the engine bay fuse box cover, clip the relay panel out you will see the connector in the bottom of the fuse box

Back again so I've contact cleaned the white connector black relays and the throttle body connector and pedal connector cleaned throttle body while I was there, went out all was good for 30 miles then around 4-5k under load its jumping and stopping there but when in neutral or clutch down it revs freely to the red line cars just had 4 new injectors as that was my first thought but its like after a good run its not getting fuel under load?

 

[Martin_172]

Back again so I've contact cleaned the white connector black relays and the throttle body connector and pedal connector cleaned throttle body while I was there, went out all was good for 30 miles then around 4-5k under load its jumping and stopping there but when in neutral or clutch down it revs freely to the red line cars just had 4 new injectors as that was my first thought but its like after a good run its not getting fuel under load?

yeah my first thought would be injectors when I read that but if its had 4 new, known good ones then it probably could point towards that connector still playing funny buggers. As the original problem seems to have gone but this one has arrived? repeat the process again id say, then coat it in contact cleaner and leave it disconnected over night and try again tomorrow see how it goes.

 

[jamiemonk567]

yeah my first thought would be injectors when I read that but if its had 4 new, known good ones then it probably could point towards that connector still playing funny buggers. As the original problem seems to have gone but this one has arrived? repeat the process again id say, then coat it in contact cleaner and leave it disconnected over night and try again tomorrow see how it goes.

Its strange yesterday it was 3k in gear revs fine out today its anywhere between 4.5 and 5k in gear only but only after 30 miles once its hot absolutely fine until hot

 

[Martin_172]

Does it only play up on part throttle? But behave on full throttle? Mine done that with an upstream lambda sensor fault

 

[jamiemonk567]

Does it only play up on part throttle? But behave on full throttle? Mine done that with an upstream lambda sensor fault

Doesn't make a difference on part or full just won't go above 4.5/5k once hot engine is holding itself back like its not getting correct fueling when in gear only