unreliable boost on 951

[Manute]

Hi, how are you all? Itīs been a while.

Iīm suffering a strange problem from a few months, and i need your assistance.

Itīs a matter with boost....it happens every now and then, letīs say one time of 10 times I start the car, just to say something.

the problem is at random, when after starting the car and warming it up, I try to push it a bit.
The car apparently runs good, but when I press the pedal letīs say more than a half and I try to increase the boost, it goes just at 1.2 bar, and the engine runs rough...so summarizing, driving slow seems car is ok, but i look for boost, and engine become rough and the boost stops at a invisible 1.2 bar barrier, always the same value, 1.2 bar.

The curious thing about this is that, when it happens, I just stop the engine, restart the ingnition and the problem goes away!! I just need 5 seconds to restart and I have full boost and no roughness.

As i said it happens at random and when it happens I solved it always restarting.

Do you have any idea????

Thanks for reading and greetings from Spain!!!

[nynor]

your KLR is going into limp home mode. there are several reasons for this. in my case, the wires from the knock sensor were cut and it would sometimes make contact, sometimes not. a bad knock sensor will do the same thing, so i replaced it and then found the frayed wiring.

i would make an LED tester for the KLR and see what it is doing when it only goes to 1.2 BAR.

[Manute]

Thanks nynor, I checked a recent post about the led tester and iīm making one (well, i donīt need to make nothing if I understood, itīs only a led....). I also checked clarkīs garage and 951racerx for the blink codes and I read about someone with the same problem as me and it finally turned to be the KLR chip.

Iīll check the knock sensor too. I looked here at pelican to replace it but didnīt find it, I think itīs not very expensive to replace just in case.Do you know were to find one?

Iīll check knock wires too, were was your problem exactly nynor?

And last thing, in case the problem is the KLR chip, were can I find a not very expensive one?

Thanks!!

[nynor]

the blink codes will tell you what is causing to go into blink mode.

i have the one i removed from my car, which is fine. i'll sell it to you for $20. you can get a new one for about $40 or $50, IIRC. pelican has them, i am sure.

the problem with mine was that the wires were frayed, about 4 inches from the sensor itself. i had to take the intake manifold off to get to it and do a repair. sometimes the frayed wires made a good contact and sometimes they didn't.

you may be able to pick up a KLR chip on ebay or from a member here that has upgraded their chips.

[Manute]

Well I had no luck finding the knock sensor here and in ********AZ, no luck with "knock" nor with "ping", if you have a link please help me.

Iīd buy it yours if itīs fine, i have no problem. Is there any way to check mineīs for itīs physicall condition apart from the blink codes?

Oh, and excuse my english....what is the exact meaning of "frayed"? burnt wires?

[nynor]

oh, wow, i didn't see you are in spain!

in my case the wires were mostly broken from age and vibration. picture a wire that has been bent back and forth so many times that it has simply started to unravel and the insulation is broken.

my extra one is perfectly fine. shipping to spain may take awhile.

they can be tested with an oscilloscope. they are somewhat fragile; dropping them can ruin a knock sensor.

try this at www.*****************.com (i couldn't find it at pelican either...):

http://www.*****************.com/SearchResults.asp?Search=knock&Search.x=0&Search.y=0

[Manute]

Hi again, i have news!

I found an led in my house so i went to try the blink codes; i ran the car a bit, and the problem appeared again....roughness, 1.2 boost.....ok, I tried the led and it blinked, a pair of blinks followed by another pair of blinks, so i guess itīs code 2-2 according to the chart.

And that means: "knock sensor monitoring"-"knock sensor supplies excessively small or no signal, or K/CP control unit is defective".

After restarting the car, problem and blink code went away, so you were right, itīs a knock relative problem.

I assume K/CP means the KLR chip, so now I need to know which one is the faulty one.

Well, I had no more time today to physically check wiring and knock sensor integrity, but since i donīt have an oscilloscope if I see nothing strange at the wires iīd better replace the sensor.

I just pray for the KLR chip to be ok, itīs quite expensive!

[nynor]

just so you know, it was so tight under the manifold, that i couldn't see the damage to the wiring until i had the intake manifold off.