OK, so been looking at Det again toady. Bear in mind, Thor O2 sensor clearly showed that this was leaning out not timing. This was on both my car and Leigh (Friday's) mine with various maps.

 

So today, replaced FPR with new one (thanks Leigh) and connected up fuel pressure gauge. Result: 3bar with atmospheric on vac line, constant 3bar + boost under load, similar story on Leigh's car. So no pressure problem, but STILL DETTING!

 

Other stuff done - EGR system disabled by removing sol valve. EGR valve works OK as applying vacuum to line when idling does make the engine run like crap. Returns to normal when pressure relased so no sticking. Possibility that valve still passes under high exhaust pressure ?? Any ideas?

 

PVPR system removed to simplify pressure feed to FPR and remove another potential problem.

 

 

Started to get a bit p'd off now so thought bugger it, will check the timing anyway. Both cars show 35° at 2000rpm! Got to thinking initially CAS is broken etc. initially adjusted Leighs to 15° which ended up with the CAS being wound right round - obviously looks wrong. From running was obviously retarded.

OK, try to figure out why timing is off. Measure MAF voltage at 2000rpm, stationary gives 1.43volts. Sure enough, TP calculated at 7, which accoding to the map should give - surprise surprise 35°. So basically timing is right for engine conditions (as measured).

 

Next measure MAF voltage at idle 1.07v, within spec of 0.8-1.5v as quoted in manual.

So basically it looks like what is going on is that the MAF isn't measuring all the air going into the engine at high revs, so it's leaning out and detting.

 

Thinking there are 3 possibilities:

1) EGR valve is passing a bit and so adding unmeterd oxygen / hot gas?

2) Air leak before turbos drawing air so it's not metering that amount. I think it would have to be a pretty big leak though.

3) MAF is a bit dodgy and is not reading the correct air flow.

 

Any ideas / comments greatly appreciated here guys both by me and leigh ...

 

Next step I suppose is try an new MAF :eek: or - try pinching the PCV hoses to see if idle is affected - apparently thats a way of identifying if it's an air leak.

Hello John

I dont know what on the car you have being looking at.

So i come with some suggiestion.

There is worth to look at the injector nossels, if one or more have bad connection it can lean out on a cylinder. Also measuring the resistance over them and the power supply. Is it on a particular rpm it detonating?

 

Cheers for the advice.

I'm pretty sure it's MAF/Air leak though due to the timing issue (35° at 200rpm).

Will check the injector resistance though, worth a look.

Cheers for the advice.

I'm pretty sure it's MAF/Air leak though due to the timing issue (35° at 200rpm).

Will check the injector resistance though, worth a look.

 

Do you mean 2000RPM? If so then 35 deg is not unreasonable. If you have a look at the timing map in the ROM you will see 2000RPM no load is 35 degrees. The ECU uses an average of the block of 4 numbers around the RPM and load you are running at.

according to the conzult manual, it says that with a warm engine, air con off, neutral gear and no load at 2000 rpm the timing should me no more than 25 BTDC.

 

Vijay

according to the conzult manual, it says that with a warm engine, air con off, neutral gear and no load at 2000 rpm the timing should me no more than 25 BTDC.

 

Vijay

 

OK, I bow to superior knowledge, although looking at the timing maps one doesn't get that impression.

 

Thanks for the info.

Hi Cosmik,

 

LOL - That info's from Eric (Lymon) who I agree does have superior knowledge - I have no idea what's going on :D

 

Vijay

Seems strange to me too, but remember the stock timing check procedure is 15° at 2000rpm so it must be there or thereabouts on the maps.

Also, last time I checked it it was 15° under these conditions!

Confusing !

ehrm..vijay, on what page does it say that ?

it should say: at 2000 rpm the timing should be more then 25BTDC..

 

-Eric

 

according to the conzult manual, it says that with a warm engine, air con off, neutral gear and no load at 2000 rpm the timing should me no more than 25 BTDC.

 

Vijay

:slap: real sorry, it does say more than 25...........................

 

Vijay

John, this might sound *really* stupid but have you checked the fuel lines under the car for crushing? Sometimes they get caught by the jack and this will certainly restrict fuel pressure at higher flow rates...

 

Just trying to think of stuff :)

 

CheerZ,

 

Andy

John, are you using a romulator/zemulator ?

 

I once had a weird problem and it turned out it was caused by a corrupted ROM image in the romulator's memory .

I had to reflash the complete rom image (not just the maps) and everything was fine again.

 

-Eric

Andy, have checked fuel pressure and it's OK all the way up to the det!

 

Eric, worth a go, cheers. Not got romulator connected up, but have got a 4 map chip in there.

Will maybe try a different ECU and build the maps onto a new base. I was using 93 man AIV remove from 310Z with all maps replaced.

If you are open to more suggiestons here comes one more, if you have a eletronic boostcontroller.

There is a hose coming from the turbo on the inlet (suction side) there goes to the stock boost solenoid valve for ventilation of the wastergate (stock setup). The other hoses that are conected at the solenoid i asume are disconected there or at another place under the process to install BC.

If the stock boost solenoid are stuck, opens during error in bin or other way.

You will have a air leak after the MAF. But then again, just a suggiestion :o)

Good luck

Cheers again for all the suggestions, I'll try to look at it again after the weekend.

john sorry to hijack this thread but do you still have the swb exhausts?

if so i would be interested

thanks

o_pike@yahoo.com

hm look like some never ending troubleshoot :)

Can it simple be wrong fuel with low octan ?

Filled wrong, or the gas station just had wrong gas on the pump/ bad gas? I likely would belive the last. There is no reason to belive the gas station never do wrong.

I have seen some do days of troubleshooting becouse of that, they filled petrol on a dieselcar :)

Happy hunting

Going to spend a day on it tomorrow (with a fresh tank of Optimax).

Hopefully will get somewhere!

hi john,

,i had detonation on my old gt4 celica - turned out to be a blown spark plug

how would that work then???? no spark, no bang , no heat equals no det

dunno but it happened and changing the plug fixed it