[Leelo321]

i have been having problems with the carly for ages now

very little boost and when she does decide to boost the levels are very erratic

i've changed to a mbc, no improvement, i've changed the wastegate actuator, still no improvement, tried another apc/di unit but still no change, however today the check engine light came on(4 flashes)is that the knock senser code my carly is a 2.3 cs(1990) i am woundering if this could have been the culprit all along? what happens when the knock senser fails? or could the knock senser just have been triggered due to erratic boost levels? this problem has been occuring now for months (seems more like forever

) however i'm determind to get this fault found, so any help/advice would be much appreciated

 

[slidejules]

Hi Lee,

According to paragraph 3 of this page, yes a malfunctioning knock detector can cause base boost only.

HTH,

Jules

 

[StephenA]

Basically if the knock sensor goes then the engine goes into a "safe" power curve to avoid pinking.. so a duff sensor certainly would keep the performance down.

But having said that, on my H reg when it was faulty it used to flash Check Engine at me when the computer worked out it was faulty.. which was usually when I was coming down the road from the top of Leckhampton Hill and was trying to concentrate on driving.

If the Check Engine has only just started flashing then its probably only just gone awol.

Steve

 

[Leelo321]

thanks very much guys, i will have a go at unbolting the knock senser as suggested in your link jules, forgot to say that this problem with the boost etc started shortly after i had the full jt 3" exhaust fitted, after reading other post regarding the jt sysyem i thought that it was down to the base boost needing adjustment, which i did but no change in boost levels at all.
i will have a go at the knock senser and let you know the result, Thanks again

Lee

 

[steisan]

Good luck!

Wouldn't the MBC have solved the boost problems if the knock sensor was bad? How can a knock sensor affect the boost when it's managed by the MBC?

 

[Carolyn Davies]

I have a 1989 9000s Turbo Auto (Jetronic). In the last few months I have had an Air mass meter and a crankshaft position sensor fitted. Last week I had a new thermostat and a radiator temperature switch (I think) so that the cooling fan would come on sooner. She is now showing 4 flashes, as you say, a knock sensor problem. What is a knock sensor? If I get this replaced will it improve the dreadful fuel consumption about 25mpg on motorways, and down to 17-18 around town? She is a lovely car but she will have to go if I can't sort her out.

 

[Leelo321]

not sure if the mbc controls the knock senser, i obtained the mbc because of a suspect apc valve, someone here will let you know i'm sure

I unplugged the electrical connector from the knock senser and the boost levels are much higher, she does boost so much better with this connector unplugged , the boost is not mighty(as should be

) but never the less it is much better with the knock senser unplugged, does this mean that the knock senser is at fault?? i want to be sure before i spend any more ££££

if yes wher can i acquire one? cheers folks,

I don't now whether this is connected but my carly is running at 18.1 miles a gallon

, on a run if i'm lucky i get 22

but i do of course give alittle

does any one know how many mpg's i should be getting out of my 2.3 carly??