Wont rev over 5k

[SkidMarx]

Recently fitted a new engine to my clio 172 FF. while the engine was out i decided to fit a 182 exhaust manifold and a sport cat. Got the engine running at the weekend but the car doesnt want to rev over 5k, when driving the car it drives well upto 5k, then the revs will drop right off, the gearshift light flashes up and it almost throws you through the windscreen! I put the car on clip tonight, the only fault present is A/C pressure sensor, which i assume is faulty because there is 0 bar in the circuit as i havnt re-gassed it yet. Thought it could possibly be blocked cat, but even with the cat removed it still wont rev over 5k. Any ideas? Has any body ever had problems using the 182 exhaust manifold + sport cat with the 172 ecu??

:S

 

[ditz]

i've got a bit of a drivabilty issue with the same setup which is just a faulty lambda sensor (either that or it dosn't like the 182 one)
got a flat spot between 3 and 4k,, but not heard of that.
is it bang on 5k every time sounds like some sort of limp home

 

[Bluebeard]

Sounds daft, but there is a lower rev limiter when the engine oil is cold. Stops you over revving and preserves the engine.

Have you ruled that out?

I'm not a mechanic by any means, but thought i'd help. Ish.

 

[SkidMarx]

It does feel like the same system as a 225, but it doesnt just rev up to 5k and stay there, it revs to 5 then dies and really throws you forward. I had a similar issue once with a blocked cat, but ive ruled that out. The cold start limit ive also ruled out as the clip parameters are showing coolant temp 80 degrees +. 1 thing i did notice was both lambda sensors changing from 80 millivolts - 800 mv. Im sure the downstream sensor usualy stays at 0 mv?

 

[mattjk]

I had similar issues with this and it was a loose earth cable that attaches to the top of the gearbox id deffo check that!

Exactly same issues with the engine just dying and gearbox light flashing

 

[SkidMarx]

Thanks guys, il clean up the earths tomorrow and try

 

[Jay Payne]

could be an earth as said.

Also have u used all the same sensors from the original engine? just wondering if maybe there is a faulty/incorrectly reading sensor on the new engine. Wouldnt nessisarily show up a fault if the ecu was seeing a figure between its normal limits, it would assume it was ok. Just a thought.

doesnt sound like a exhaust prob if the gearshift light is coming on

 

[SkidMarx]

ive used all the sensors that were on the new engine..altho my 182 manifold came with an oxygen sensor which ive left in...could be faulty, altho i wudnt think it wub cause this type of problem..will try cleaning up the earths and maybe swap the old sensors if that doesnt help. Maybe the dephaser solenoid on the new engine is faulty?? altho i thought i wouldve flagges up a fault on clip. Thanks guys that gives me something to look at

 

[Jay Payne]

de-phaser cuts in at 1600rpm ish iirc

 

[SkidMarx]

Im just gettin a bit desperate to be honest, checked most things tonight ( although forget to check earths )

Its bound to be something silly!

 

[bmh.01]

I'd go with earths at the moment, check them as they always present funny problems like this. It isn't limp home mode as that is a 3krpm limit and it just crawls up to 3k its nothing like hitting the limiter at all. The cold engine limit is 6500rpm instead of the normal 7250rpm so it isn't that either.

 

[brisa4984]

Sounds daft, but there is a lower rev limiter when the engine oil is cold. Stops you over revving and preserves the engine.

Have you ruled that out?

I'm not a mechanic by any means, but thought i'd help. Ish.

only brings it 500 revs early iirc so should really still go over 5 k. :s

 

[SkidMarx]

Went out to the car tonight after work. Cleaned up the lower front gearbox earth, tested still the same!

Cleaned up the upper gearbox earth at the rear with a bit of emery cloth...bingo! runs a treat! all that messin about for something that silly. Thanks Mattyjk and everyone for the input. 5 heads are better than 1! Now the fun can begin running it in and remap!

:rasp:

 

[Mark One]

i shouldnt imagine a 182 lambda would cause this problem, but i do know that the 182 and 172 upstream lambdas are different.