It was misfiring above 4k rpm, also had code 34. I rewired the connector and reset the ecu, no more code 34, all clear. Changed the maf and the misfiring stopped on low boost but still there on high boost. Also got code 34 again!

 

When it misfires i cant hear any rattling, its just total power loss.

 

Im going to change the plugs next but its really starting to pi** me off!

 

What percentage should my a/f be at idle and full throttle?

 

Is my car detting?

detting won't cause a code 34, 34 only means there is a problem with the det sensor circuit.

 

As for misfiring at high rpm, might be plugs, bad PTU maybe.

changed the maf, ptu etc

 

plugs are next.

 

Does detting not feel like a missfire / full power loss when it happens then?

 

Ed

Also if im getting 34 will it effect my a/f mix and timing? Could this itself be the cause of the misfire? My car has no safty boost unless i turn my controller off for a while. 13psi with the ecu running code 34, could that be the cause if the misfire at high rpm?

if u av code 34 det sensor or knok sensor detects detination then ecu will go in to safety boost and it also will retard the ingniton timeing so it wiil have loss of power and miss fire maybe mine had this fault and wen i try ed to wack boost up to 1 bar it missed under hard boot not checked for coads yet

will to moz

but is code 34 det sensor fault or dett has been detected?

well ill change the plugs and if its still the same its going to mickyb

but is code 34 det sensor fault or dett has been detected?

 

det sensor fault - it is NOT a code for the vehicle actually detting

so would detting feel like a total loss of power? I cant hear it rattling so maybe its not detting.

 

The only thing that bothers me is that I only get code 34 after hard driving. With the ecu reporting this code will it effect my a/f ratio and timing enough to cause the misfire on high boost? (i use a pro spec 2 and john dixon chip/map)

I have never experienced a noticable loss of power under detonation, although I presume there must be some.

so would detting feel like a total loss of power? I cant hear it rattling so maybe its not detting.

 

The only thing that bothers me is that I only get code 34 after hard driving. With the ecu reporting this code will it effect my a/f ratio and timing enough to cause the misfire on high boost? (i use a pro spec 2 and john dixon chip/map)

 

iv e had his pro ie code 34 and ad to put new wireing from ecu to top of engine and do the risistor mod as well till i can get wound to doin the kock sensor its self cos 1st it had intermitent fault on wire now knok sensor has or wires from it wen i get 34 i get loss of power

well at least its not detting then.

 

Im going to change the plugs and reset the ecu again

 

If i get code 34 again ill either put a resister in or take it to mickyb

well at least its not detting then.

 

Im going to change the plugs and reset the ecu again

 

If i get code 34 again ill either put a resister in or take it to mickyb

 

pluged mine in today still av code 34 so need to find out the correct value ov resistor p***sing me off now :cry:

 

good look edk83

Me too! I am looking at bypassing mine now.

My car did the same thing, this is what it was on my Z.

http://www.300zx.co.uk/forums/showthread.php?t=78587

Code 34 = fault in dett sensor/wiring

 

Code 34 on some chips will cause SERIOUS hesitation above ~3k rpm

 

Missfire on high boost is usually caused by a faulty connector on one of the coilpacks or the PTU.

 

Get rid of the code 34 first then work from there ;) Resistor value is 1Meg Ohm but beware as this removes the ability of the ecu to protect the ecu from bad fuel. The operating conditions the dett sensor works in will not protect your engine from over boost. IMO it is still worth keeping though due to the crappy fuel we sometimes get over here.

 

Sounds to me like you have either bad wiring in the main ecu harness (replace wires between sensor and ecu connector) or the ecu connector is not seated correctly....

i cut off the dett wire connector at the top of the engine and soldered the wires together. I then left the batt off over night. Ran the engine for 5min then checked and no errors.

 

Drove the car some more and it came back after a day. The problem is more hesitation than misfire. Doesnt sound like a missfire, just a total power loss and refuses to accelerate. Fine on low boost tho, now i changed my maf. It feels just like it did when the maf was playing up but only happens on high boost.

 

Im going to change the plugs at the weekend just in case and maybe try yet another maf.

 

I use a john dixson chip and greddy boost controller so no safety boost. I asked before if code 34 would cause the ecu to change the a/f mix or ignition timing as it feels like its down to something like this. + it only does it above 3-4k so sounds like your right. Was the same when it was the maf, only above 3-4k rpm.

 

What im really worried about it melting a piston etc if the mixture is wrong and i keep nailing it to test it.

 

Ed

I'm 100% positive that your problem is caused by your code 34! Exactly what happened on mine. You don't have a miss-fire so hold on with the plugs.

 

You can't just connect the wires together, the ECU will see a short circuit and generate a code 34 error ;) You MUST use either a new sensor OR a 1 Meg Ohm resistor in its place to get rid of the code...

I just cut the connector off and connected the wires together as they would be in the connector as i thought the connecter was bad (moving it seemed to make a difference).

 

I will clean and reseat the ecu connector this weekend, I have already ordered the plugs from smithy as want new ones anyways. I'll do the resistance test to check the wiring to the ecu etc and probably do the resistor mod for now, after that I'll try yet another maf.

 

What im really worried about it melting a piston etc if the mixture is wrong and i keep nailing it to test it.

 

Thanks for your input mate.

Its not your MAF!!! ;) LOL

 

The problem isn't at the connector on top of the engine, the problem is the connector that goes directly onto the sensor (which you can't get to). Just bang the resistor in the connector and take it for a test-rag ;)

lol ok! Its just that changing the maf stopped it on low boost and it felt very much the same.

You had 2 faults before then ;) LOL

lol yeah, or two things causing the same fault as both bad maf and code 34 screw up the a/f mix and timing.

Yep, the ECU assumes dett under all conditions if it detects an error with the dett sensor. This puts the ecu into its detonation maps which increases fueling and retards the timing - in some cases so much that the engine hesitates badly....

well thats put my mind at rest a bit. as long as its running rich not lean.

well thats put my mind at rest a bit. as long as its running rich not lean.

 

Yep - SERIOUSLY rich!!!!!