clubracer6

I purchased a 951, which after 2 months of mechanical restoration (new belts, tensioners, water pump, power steering hoses, front engine seals, transmission seals, all (12 or so) coolant hoses, radiator, alternator, turbo intake hose tires and some other small misc stuff)I am finally driving it.

Engine Modifications include - the Huntley Stage 1 MAF, ARCII w/ARM1 fuel/air ratio meter, Huntley adj fuel regulator, Huntley manual boost control. There's probably a bit more but those are the basics.

When I picked up the car the boost was cranked all the way up to 24/25#. I immediatly turned it all the way down and am running around 17# give or take a couple of lbs.

Tuning this car has been a huge pain in the ***. I have some dyno time coming but haven't made it there yet - to get to my point.

My main issue is the car leans out at full throttle above 4k rpms. I had everything dialed in perfectly and maybe drove it 2 times w/no issues. Suddenly the the ARM1 goes from the last two blue lights and drops to red as soon as I get around 4k at full throttle. If I feather the throttle it dithers nicely or goes back to rich. I have tried the high **** turned all the way to the right and that doesn't help at all. Some times during my adjusting the car jerks and bucks pretty violently.

Any thoughts on this?

Also, I am really contemplating taking the MAF stuff out - I love power but I want decent drivablitly so that if my wife wanted to she could drive it w/o me worrying about her.

How hard would it be to get out? Could I still get 15 to 17# of boost w/o it?

thanks in advance -

Alex

IanM

I also have a Huntley MAF, ARC2, etc, and I'm very happy with it. I dialled it in with a wideband O2 sensor, and I haven't had to touch it except for after making additional mods to the car. Once you're under load and the ARM1 shows 1st or 2nd blue light rich conditions, the only thing that should make the ARM1 display go full lean like that would be if you took your foot completely off the gas. Perhaps this problem has something to do with a faulty throttle position sensor? Or perhaps there's a loose connection on the ARC2 wiring.

I'd be worried about the fact that the previous owner was running such crazy high boost, on a car that was also running lean at the top end!! That's insane!! I wouldn't recommend running more than 16 or 17psi, and that's AFTER you get things dialled in properly.

Do you have a fuel pressure gauge at the end of your fuel rail? If not, how do you know what your afpr is set to? I'd set the afpr to about 40psi at idle with the vacuum line disconnected as a start.

Are you running stock chips?

smkn951

i also have the same set up, with the eception of i have a fuel rail guage. dont' know if it's accurate, but i got it onj or about 40-45 psi(it bounces), i don't have a wbo2 still saving $.
when my car would do this i simply turned douwn the boost, it's pretty low, don't know what psi tho, but it seems to run fine. i also went as low as i can on the fp w/c reads 40-45 psi.
according to smog last year, i was running rich and no matter what i did it still won't pass till travis dialed it in and adj the switch in the dme and adj the air via unplugging the hole in the air fuel monitor.
also are your plugs built up with a lot of carbon?
can't seen to figure this out on mine, i clean mine at least monthly when it starts to idle rough.

clubracer6

The car didn't start leaning out until just a couple of days ago. The fuel pressure is at 40. Maybe it is the wiring - because a couple of times that last red light goes dim then out. Is your ARC2 in the glove box? I sometimes think if would be better under the stereo. I don't know about the chips - there is a reciept for a chip, but then it looks like it was returned. With that kind of boost i assume it does.

thanks for your input

Alex

clubracer6

I do have new plugs/wires and the fuel rail guage. Maybe something came loose in the wiring. The lean thing started on a day where earlier in the day the car was hitting full boost and staying rich to red line.

washington951

i have a similar setup - the only time that i have had REAL problems is when the wires from the O2 sensor got brittle and cracked. the readings on the ARM1 would go nuts. basically it was a bad ground, but i took the opportunity to install a new 02 sensor and re-do the connections from the sensor to the wiring harness - soldering and double heat-shrink. no problems since. you might start by checking the wiring from the O2 sensor...just a thought.

PorscheLars

"also are your plugs built up with a lot of carbon?"

Which injector size du u have?

Just curious

IanM

Alex,
My ARM1 display shows full lean (red) when my foot is off the gas. Sometimes the light stays on, other times it tends to fade out. But as soon as I'm back on the gas it'll start dithering back and forth properly. I'd say you need to find someone with a wideband and do some tuning, either on the street or on a dyno. I prefer street tuning myself, but I'm lucky enough to know someone with a standalone Motec wideband. Do you still have that testpipe? If you stick a wideband up your tailpipe, it'd give more accurate readings if you were running without a cat.

Porscheman101

When I installed my Huntley stage 3 MAF with the ARC-2, I would get really lean under heavy acceleration. So what i did was order a new O2 sensor. I got mine from huntley. After i got the new O2 sensor in the ARM1 dialed back and forth like normal. So thats what happend to me.

clubracer6

Well maybe that's what happened - my 02 sensor just crapped out.

I have no idea what injectors I have - I need to find out what they are.

No test pipe either, but do have access to a good dyno w/all the metering equipment.

Alex

washington951

my bet is the O2 sensor or the wiring to/from the O2 sensor....
take the opportunity to put a new one in - consult huntley on this - don't forget the anti-sieze.

one tip - unplug the sensor wiring from the harness at the firewall - inboard of the fuse box - tie a string to it, lower the plug and extract it from below. remove the sensor, untie the string. LEAVE the string in place. cut the plug off of the old O2 sensor (the one that you unplugged up top) but leave as MUCH of the wiring as you can, as long as its good - solder in the new leads from the new sensor - heat shrink, etc... - install sensor, re-tie string to plug and pull the string from the top to easily re-route the lead. untie string - plug in - enjoy! (this is WAY too long a post for this procedure!!!)

good luck!

jimbo1111

Club racer6 When running that kind of boost it's very easy to blow a vacuum hose. Check your lines that go to the fpr before you spend all of your money.

smkn951

don't know what size inj i have. will getting a hotter ign sys fix this gremlin? also bfeore i had to mess with the o2 wire when my idle wasn't steady.

clubracer6

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by jimbo1111:
<strong>Club racer6 When running that kind of boost it's very easy to blow a vacuum hose. Check your lines that go to the fpr before you spend all of your money.</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">You have to bear w/ me I'm new to the 951 scene... FPR = Fuel pressure regulator?

jimbo1111

Yes fuel pressure regulator. Check to make sure that all off the vacuum lines are connected and are not leaking. Since we have a rise rate fpr on boost the vacuum lines get pressurized and if they are old or not secured properly they will pop off. In that case the fpr will not see boost and will deliver a fixed fuel pressure instead of a rise rate. this would cause you to go lean in the higher rpms. Normally fuel pressure rises with boost.