running lean all of the sudden

[MATT41178]

OK

I have had my car running for almost a year and I just took of the cat for some drag pulls, It suddendy goes really lean at idol, I have a JWT ecu and SAFC, even whene I change the settings on the safc it will still leant out really bad at idol unless I feather the throttle a bit and some times it will take about 30 seconds to get it to run right at idol some times it will lean out and die, also while I am crusing the AFR's are unstable 14.3-15.8 it never did this before I took of the cat, I also ran without the cat after it was first rebuilt and turbocharged and It was fine running very solid at idol,I have tried to reset the de cel on the safc and still having this isuue,

Any help anyone can offer would be appreciated

[LEMHEAD16]

I am having a very similiar problem, lean Idle and all. I am thinking that it is the mafs. I am going to switch it out with a friends today so I will let you know what happens.

Mine also happened right after some racing except I was doing an Auto-X not drag

[GEO]

might be timing?

[MarkEmark]

OK

I have had my car running for almost a year and I just took of the cat for some drag pulls, It suddendy goes really lean at idol, I have a JWT ecu and SAFC, even whene I change the settings on the safc it will still leant out really bad at idol unless I feather the throttle a bit and some times it will take about 30 seconds to get it to run right at idol some times it will lean out and die, also while I am crusing the AFR's are unstable 14.3-15.8 it never did this before I took of the cat, I also ran without the cat after it was first rebuilt and turbocharged and It was fine running very solid at idol,I have tried to reset the de cel on the safc and still having this isuue,

Any help anyone can offer would be appreciated

My car was hitting high 17's/low 18's at idle after the flex pipe that ran from the downpipe to the EGR valve broke...but idle was the only A/F affected; everything else was rock-solid. But it also never came close to dying, even with the A/Fs that lean...

Cruising in full vacuum you should be at about 21:1

Try putting your cat back in to see if it runs the way it did earlier...although just removing a cat should not cause what you're describing...(it shouldn't cause anything actually, except maybe a CEL if your 02 sensor is disconnected)

[MATT41178]

I found the problem, It was the timing.

Thanks

[LEMHEAD16]

What do you mean it was the timing? Did you adjust it? Was it to far advanced or retarded? I have to assume mine is not a timing problem because it is intermitant(sp) Unless my dizzy is going bad...hmm how would I check that?

[MATT41178]

It was not the timing, but my timing was off, one of the bolts on the dizzy was loose and timing was at about 30 BTDC,

I am now still having the same problem.

does anyone know if this could be the coolant temp sensor or how to check it?

[GEO]

It seriously sounds like pre-ignition.

[MATT41178]

What is pre-ignition and whay wuold cause that?

Also I just changed my CTS and now AFR's are solid but still goes real lean,

And another issue is that I just tried to chang settings on my SAFC and it dosent work wich is telling me MAFS?

[LEMHEAD16]

What do you mean it was the timing? Did you adjust it? Was it to far advanced or retarded? I have to assume mine is not a timing problem because it is intermitant(sp) Unless my dizzy is going bad...hmm how would I check that?

I was goign to preface this post with the fact that i swapped MAFS and FPRs and still ahving the same problem.

[DammitBobby]

JWT 72lbs +SAFCII +750cc injectors

Dam I am in the same boat. I just rebuilt my engine and my AFR`s at idle are pegged at 21. I can`t get it to adjust any lower. I am going to look at my fuel pressure gauge tonight if I get home early enough. I had no problems with this same setup before I rebuilt my engine. I am wondering if I should reset the SAFCII to default settings and start over. My current SAFCII settings 5in 5out 1 and 1 for Hotwire.

[GEO]

Yeh, check your fuel reg as stated above. Pre-igntion is when the ignition is firing too early thus creating heat in the chamber making lean conditions.

[Florida240sx]

Idle a/f ratio doesn't really matter. If it's too rich it could foul your plugs. Mine is 14.7 at times and 16.7 at other times. It jumps back and forth.Is your exhaust hooked up? Or open cat? Open Cat will affect your readings. Not enough pressure. At WOT your flowing enough to where this won't matter. But at cruising it COULD but shouldn't be much.I set my cruise control and my a/f ratio jumps back and forth.

[MATT41178]

well after changing the coolant temp sensor my AFR's are much more stable while crusing and at idole.

But now when I let off the throttle The AFR's go verry rich down to 10 for a few seconds and sometimes to 8 wich I know Is not good.

Now back to the MAF and the SAFC not working, I just found a brand new in the box MAF on ebay for $175.00 and puchsed it, I shuold have it by friday I will put it on and see what happens, and post results.

Does anyone know why my safc would not work ?

If the new Maf dosnt change anything I will have a used z32 N62 (with the orange sticker for sale)I will keep the new one on my car for better reliability.

Aso as for checking the dizzy I know mine is good I put a brand new one on recently the crank angle sensor went out in the old one, and whene that happend my car would just die while driving for no apparent raeson that was a pain to figure out.

why would I be having preignition other than my timing being at 30 BTDC?

Fuel pressure at idole is solid 34 psi.

[Florida240sx]

What you mean your safc doesn't work? Explain to me.....Anytime you let off throttle your A/F ratio will hit rich for second and then go lean. Because fuel is still being sprayed but less air is coming in. My car hit's 9's when I shift and foot is off the gas. Is your exhaust hooked back up?or still open cat? Unless your at WOT you won't get accurate readings.

[MATT41178]

I have NE1 set at 1000 and bofre I started having these problems I could adjust AFR at idol but now whene I turn th knob to raise or lower I does not change at all.

I am still running without the cat (I have a full exaust on I just put a test pipe in place of the cat.

And whene the AFR go down to 8-10 it will stay there and just about die unless I bilp the throttle and then they will back to normal (14's)

[MATT41178]

I changed out my MAF sensor last night and now it is even worse, but my safc will adjust the fuel now and I have to have the settings At +10 to hit 14.7 AFR at idol and whene I drive the car crusing the AFR's are now going to high 16's to 17's and have to add alot of fuel to correct it, Before I didnt have to add anything at low throttle the ecu did it all.

I am totally stumped on this.

[DammitBobby]

I am running JWT 72lbs program with SAFCII and I couldn`t adjust my SAFCII after rebuilding my engine. Everything worked fine before. I found my problem yesterday and a vacuum line was open. After blocking it off it started to idle normal and I was able to adjust my SAFCII. Before I found the vacuum leak it would idle 21-19 even when I turned the SAFCII to +50%.

Now at Idle I have my SAFCII around +20%.