wildy

i put a thread on here a while back regarding my XR2I, the Rev limiter cuts in at 4800rpm, this was combined with bad fuel ecomomy and a poor idle, we established that it wasnt in limp home mode.

I bought a FAULT FINDER, and this indicated there was a fault with the Co Pot......i replaced this, and the idle has improved and the fuel ecomomy is marginally better ..i presume it might have been over-fueling on idle? i then used the fault finder again and the error had gone

However the rev limiter is still vey low, but oddly enough, u can rev the egine to say 6500rpm whilst not in motion...but when u are on the road and driving in gear it will still cut in at 4800rpm...if u dip the clutch whilst in motion and rev the engine then it will then rev to the 6500rpm mark easily.

Any further help on this would be greatly appreciated

1.9 xr2 on 40's

so its limiting only when under load?

weird

i havent a clue what it is mate

map sensors play up sometimes they work better when just unplugged rather than broke and connected
up plug urs and see what hapends

L33 BYT

Know this sounds silly but is it actually Rev limiter and not a miss fire here.

wildy

ill go out in a minute and unplug the Map sensor and see wot happens.

I suppose it could be a mis-fire...it is very consistant if it is, and is defo only evident when under load...not to sure wot the rev-limiter on these cars is like, the only way i can describe it is a very Soft Cut and it is possible for the revs to climb above it if its held on the limiter for a while i.e it kicks in at 4800rpm but if i hold it there it will climb to 5000rpm

L33 BYT

U changed the silly bits like Plugs/Leads? May be worth doing a compression test also. see what results you get from this. Then it is basically a case of testing individual components and swap testing things like your ECU, Map Sensor Bla Bla Bla

1.9 xr2 on 40's

sounds like maybe a injector problem??

could be runnin out of fuel pressure?

i u wanna buy some parts to test, i have em all nice and cheap

Jim Galbally

does it do it in 1st?

does it get worse in higher gears?

any kinks in the fuel lines?

MikeyXR2i

hmmm, i got a funny feeling a valve might have burned in it causing to pop and fart when under load. Compression test as mentioned above.

wildy

ummm...thanks for all your replys and help...

the limiter (if thats wot it is) will kick in through all gears, the car struggles to reach 80 in forth..........it feels very underpowered...although it does drive fine...
just not quickly lol

as far as i am aware the ignition circuit regarding leads and plugs is ok

so next thing is to do a compression test...ill do that tonight and post the results

I did un-plug the MAP sensor and try the car...the limiter went down to 4000rpm and returned to 4800rpm when re-connected

MikeyXR2i

Sounds like a valve burned or something head related.

wildy

i finally got round to doin a compression check

all cylinders except the one nearest the cambelt read 200psi, but that one read 180psi....not sure in that would cause the problem though

me and ryan took the car out and it is indeed a mis0fire and not the rev-limiter...i have rep[laced the plugs/leads/coilpack/map sensor....just to be sure

looks like i will need to remove the head and investigate further :-(

thanks again 4 the help

wildy

well...as an update, i took the cylinder head off at the weekend, onE valve was indeed heavily pitted and there was evidence of the valve not seating correctly (this was on the cylinder with low compression). i replaced that valve and re-ground all the others

took the car out, and it was exactly the same...still a mis-fire

interestingly though i disconnected the throttle position sensor and the mis-fire almost went...it will rev right upto the limiter, with a slight hint of mis-fire around the 5500 mark...so it looks like im heading in the right direction to finding the fault at last, although the KAM didnt register a fault with the TPS??? so maybe its not that? any ideas on checking the TPS?

AndyRST

at a guess could the misfire have caused the damage to the valve and valve seat in that cylinder? and not the other way round i.e the valve been causing the misfire.

Sounds like you need to find the fault before it damages anymore of the engine.