timichaud

hello ! dont tell me about my english cause I'm french haha thank you!

I've build a Borgwarner 256 turbo cobalt for my brother with 3rd Gen block and wiseco pistons and zzp rods, ZZP intercooled, external wastegate, ZZP ported head with stage 2 cams ,springs, valves and big fuel lob. Lot of other pieces in the car.

Runs fine for 1 summer and suddenly the car cuts like anti-spin protection (but not enable)
the car run like **** 5000rpm to 7500rpm.

here's snapshot of my logs before the problem and with the problem


this is a normal running condition



here's you can see that MAF spike from around 350g/sec to 580g/sec




I've checked the injectors seal and look normal
I've swaped the MAF with an other LNF with same problem
Swaped spark plugs
This is not the gas too...
Put a brand new battery in case of low voltage for the sensors...same problem

Do you have an idea???
The car act like this even if boosting 10psi or 30psi or whatever

Thank You!

ItalianJoe1

iTrader: (10)

The only thing that can cause a huge spike like that has to be an electrical issue, there's no way the sensor is actually seeing that much more air.

How are your engine bay grounds? I'd investigate all power and ground connections under the hood to make sure there is nothing loose or corroded. Seems more like a voltage spike when it happens.

ECaulk

iTrader: (6)

I second the grounds, also check the battery out too.

Just a general comment on lnf tuning, lean it out, the lnf likes it leaner, you can run .86 to .88 and log the lo res boost or map sensor I didn't see it on the screen shot

ECaulk

iTrader: (6)

Also your English is better than my French.

timichaud

power enrichment is already at 0.84 lambda and already a brand new battery !

I will recheck the grounds again and ZZP tell me that can be condensation in lower charge pipe and I have relocated MAF because of the ZZP intercooler kit with the BOV

ECaulk

iTrader: (6)

That certainly can cause the issues, pull the MAF to check for water on it.

I was saying set the power enrichment to 0.86 lambda and you'll make more power.

blueLNFftw

iTrader: (16)

plus 1 on the .86 Lambda.

It can, but it would clear up after a few spikes. I deal with this on long trips sometimes with temp changes and rain.

timichaud

The map sensor is log in the same layer of the MAF in kpa

And for the lambda it's set to .84 just to be much safe because we just have 91 octane in rimouski and high boost

I don't have pyrometer on the downpipe to know the combustion chamber temp...this is an other things why set to .84

But I know that to much fuel can be bad too hahaha I will try .86 to .88

ECaulk

iTrader: (6)

You need the lo res map, not the straight map sensor that tops out at 255kPa even with the 3bars at least in the log and the ecu.

You'll be fine running 0.86 on pump, direction injection is completely different for fueling than a port injection engine is.

blueLNFftw

iTrader: (16)

Your logging a MAP, just not the right one.

Lean it out still, adjust spark.

Did you check the maf and pull out the IC to check for water in it.

timichaud

The problem is bigger than expected haha! one roller of the hydraulic lifter is broken and the cam is now good for the garbage! this is a pre-assembled ZZP ported head so zzp tell me to ship the cam and they will replace my cam and the lifter and rocker!

the MAF spike are probably because of only one exhaust valve of the 2 open in the cylinder one

thank you every one

rnjmur

glad you figured it out. I was going to suggest that it looked like compressor surge but a blown lifter will do the same thing.

I also agree with the other posters, no reason to be running so rich. You will make more power running a leaner lambda and retarded timing then to running a richer lambda with more timing advance. There is really no need to run richer than .86 lambda. If you are worried about cylinder temps then use the COT (Catalyst Over Temp) tables to command a richer lambda only when you think it might be necessary.