TonyFlow

Friend is having problems with his mY99 UK car (stuttering under WOT, dodgy idle etc). Guessing it to be either lambda (has had a 32 CEL code) or MAF. He has full decat, HKS induction, Tek 3 remap. I have run some logs using DD, but without comparing them to a known working motor, am having some difficulty working out what the problem is!

If anyone could be so kind as to have a look at the following logs:
http://www.compass-systems.co.uk/deltadash/mg/
I would be grateful (alterantively if you could just tell me what voltages should be seen, that would be a great help!).


Cheers

malinen

I took a quick look and at there seem to be some detonation/knock between 2000-4000rpm, ECU is pulling back timing -2.0 degrees, throttle is open 78%, Ignition at 17 degrees

TonyFlow

thanks for your comments, as it sensing det, at a fairly low rev range, I assume this may point to a knackered Lambda (and possibly MAF)?

malinen

I'd check them, just to be sure!

TonyFlow

does the MAF voltage look OK - again as I have nothing to compare to, i am unsure! It looks to increase voltage as revs/boost rises, so I assume that the MAF is poss. OK! The fact that it has thrown a CEL32 (o2 sensor) obviously points to lambda, but i thought a knackered lambda would lead to running rich (and not lean - hence det)!?

SiHethers

The O2 sensor is definately failing, but it is difficult to comment on the MAF unless you take a log under full throttle from say 2000-6000rpm in 3rd or 4th gear. Then I can compare it to logs I have from MY99 and MY00 cars. I saw one MAF voltage of 4.24V at 4-5000rpm whilst at WOT which would be about right

Simon

SiHethers

I've had a closer look at the logs now and the MAF is failing too. 4.12V at 5400rpm 100% throttle, at 1 bar of boost (2bar MAP) is too low. Should be in the mid to high 4.2s. The ignition isn't too advanced though, and there isn't a lot of knock correction, so the ecu has probably switched to the low octane map. The fuel IDCs are on the lower than would be expected (but not for a MAF of 4.12V)

simon

TonyFlow

thanks very much, best get him to change both ASAP then! (or leave it and risk having to get a new engine?)

I assume if it needs to be driven - off boost is advisable?

Anyone got part codes for MY99 MAF and Lambda please?

Jay m A

iTrader: (2)

MY99 MAFs don't react well to induction kits, K+N seem more friendly than others.

TonyFlow

Jay, ive read the horror stories mate, but bob rawle supplied & fitted the HKS - so it its what it is mapped for - dont want to change too much just in case! Mind you if it has done 3 years, the MAF jas lasted a lot longer than some peoples who have standard intake!

TonyFlow

just logged my STi5, and can see the differences between lambda outputs (huge i.e. my car will read up to around 0.8v and back down - whereas these logs read around 0.3v most of the time) and Maf outputs (mine reads slightly higher voltages at similar revs)!

Parts will be ordered tomorrow!