cozmo kraemer

'94 with Street Port
still sequential
ported and balanced stock twins
downpipe
mid pipe with high flow cat
racing beat catback
"custom" intake box

PFS purple is the engine management
Fuel pump is supposed to be a Bonez upgraded version
Stock fuel injectors

77K miles on chasis....1500miles on rebuild.

Put the car on the dyno last week to try to verify the previous owners claims. I tell the dyno operator (very competent guy I trust) to be very cautious with the car.

DynoDynamics dyno

Car started the run running about 14:1 afr, at the transition (4500rpm) it went down to about 13.5:1 then started climbing (steady slope) where it peaked at 15:1 at 6000rpm. Rich was letting off at this point. The car was only making about 6 psi of boost with the normal dip then recovery at 4500rpm...holding 6 psi all the way till he let off.

The good news is the car still laid down 262 hp at 5200rpm with only 6psi and tuning issues.

My question is: What would cause the car to go so lean? When the car is at normal operating temp the idle exhaust smells like a hairdryer...just hot air (does not smell of fuel). I am real worried that something might be terribly wrong...but it still starts right up. I have had hunting idle issues, but I bumped the idle to 1200rpm (using the coarse adjustment screw) and it is pretty steady since then.

Could I have vacum leaks? Would the car run a good boost patern if it did have vacum leaks (I realize I am running very low boost)? The car also makes like a throat clearing type of noise from the intake box when you rev then let off, anyone have any idea what this is?

i will post both charts (owner's provided vs. my results tonight when I get home)

XSTransAm

Clogged fuel filter, poorly mapped ecu, check to make sure you boost hose to your fpr is attached and not leaking or clogged.

does the throat clearing noise sound like a mooo? could be your airpump

rajeevx7

iTrader: (11)

Do you have the hand held controller for the ecu? With it you can easily find out exactly what your fuel is doing at what ever RPM. And it displays your injector pulse width and %.
Also, great numbers...but that is because your are so lean. Once you richen it to the correct AFR, your numbers will decline.

dubulup

6psi won't even make the transistion to both turbo's

cozmo kraemer

Well maybe it isn't even transitioning but it has the classic transition dip then recovery.

I have the handheld controler but I havent even looked at it. The car was supposed to be fully tuned when I bought it.

I was thinking it maybe fuel pump related. Where are the injectors located? I would be willing to pull those have them cleaned and freshened...is it a tough job?

The throat clearing noise does kinda sound like a "mooo" I thought it may be airpump related...is it anything to worry about or fix?

alberto_mg

it's probably tuning. whenever you buy a car with a recent rebuild you are always gambling that you just picked up someone else's problem. the lean mixture might be what caused the last motor to go.

i don't know much about that ECU, but i'd say go to the regional forums and see if you can find a tuner in your area that can tune that ECU or someone local who knows how to use it and can help you learn. or learn it yourself but be careful - rotaries do not like bad tuning and do not like to be run lean. all it takes is one ping and you're looking at another rebuild. i wouldn't even boost it running that lean.

one more thing. might want to go ahead and change the fuel filter anyway. preventative maintenance is always a good thing.

dubulup

you can tune it yourself, if you have use of a wide band...

https://www.rx7club.com/showpost.php...68&postcount=2

cozmo kraemer

Maybe a dumb question...but how do I run no boost?

I know it will be wastegate related but are there any links I can go to in order to learn how to work on it?

dubulup

just keep your right foot off the floor...thats the safest way to run no boost

cozmo kraemer

Well I haven't been about 4000rpm since I learned about the problems.

My daily driver is occupied so I have had to drive the 7 to work for a few days. After I get my 3 series back the 7 will be parked.

The dyno operator, and myself, seem to think this goes beyond tuning. Have any of you ever seen tuning right an AFR that is that wrong?

DaveW

This may be a stupid question, but:

How were you measuring the AFR's? Was the meter or instrument calibrated recently?

Is it possible the readings are wrong? Those AFR's would be lean enough that I'd have thought you might have had detonation, even with the low boost readings.

tcb100

You need to figure out how to adjust fuel, timing and boost with the hand controller. I can give you a couple of basic maps from my PMS unit that ought to put you in the ballpark. I have the interacq program on my laptop so I have no idea how to use the hand controller.

You can get the PMS user guide at

http://www.pfsupercars.com/

cozmo kraemer

I have the guide. But I have no way to measure air fuel...I also have the interacq program and a laptop, along with the controller...so I think I am covered as far as that goes.

I still pose the question, "Can tuning alone be responsible for such high afrs?" I would think that the stock ECU would run richer than what it is running right now.


The dyno had 20 other cars go through it that day. The AFR was accurate for all of them. I figured myself to be safe in assuming that it was accurate for my car as well.

dubulup

go look at the maps loaded...and yes tuning can get A:F's that high.

tcb100

Setting one on the PMS is stock by the way, at least that's the way PFS sent them out so there would be no change from the factory ecu maps.

Load the map into interacq and look at it. The map is % increase over stock. Map 1 should be all zeros.

When you were dynoed which setting did you use? Setting 3 is race gas only.