Well I got my car dynoed yesterday and to my surprise im running really really lean, my fuel setup= 555, 255, and the jwt ecu programmed for those aling with a z32 maf. This run was at 4.5 psi, the hp,torque should be higher than what i have because its not tuned. Tune job this sat along with the mevi install.

 

Do NOT boost your car if that is your real AFR... you need to do something to fix that. That is a time bomb with a very short timer.

Something to consider though, tailpipe sniffers (if that's what this was) are usually less accurate than a WBO2 installed further upstream, also any exhaust leaks upstream of your O2 sensor can affect readings. Regardless, based on what I'm seeing here, your car is absolutely unsafe to drive in boost right now.

 

Yeah i know, i need to get a wideband 02 asap and get it tuned right away, no boost for me for the next 2 weeks. I gotta go over my exhaust system to make sure there are no leaks, but i dont think there are so well see what happens, its a good thing i got it dynoed now to see what a/f is because ive been doing a LOT of biisted runs in the last 3 days.!!!!!!!!!!

 

if that is accurate then that looks very dangerous. Do you have a cat on your car when you are dynoing? These reading are from a sniffer in the tail pipe right?

 

What are you using to tune? Emanage/safc? Do you have a AFPR, if you do maybe you can temporary richen the FP to bring down AF. Anyways, good luck and let us know how it goes.

 

JWT-ECU Time to call up Jim and raise some he**...looks like your ECU is programmed wrong, WAY wrong....those AFR's are really ugly to even look at...

-matt

 

No cat just a straight test pipe, yeah i gotta get it tuned and see whats going on with me.

 

When you say you've got to get tuned, how are you going to tune it?

 

Oh i got safc2, and hopefully by the ned of this week a wideband 02, but if not wideband by end of this week then just safc2.

 

Oh my, that is very lean. I'm surprised the dyno guys didn't shut it down. Get that wideband on ASAP, once you tune your car you should put out some decent numbers!

 

You may need more of a correction then the Super Air Fuel Controller can provide. You might need an FMU possibly

-matt

 

I don't think safc can adjust the AF to a safe level for you without affecting your timing. I have read in many thread regarding the safc correction level that more than 10% will affecting timing one way or another. with your figures, let say your highest figure which is 14.8 to bring down to a 12.0 AF: you would need at least +23% correction.... 14.8/12=1.2333

*someone confirm my calculations, I may be wrong...

I think you may need a APFR or FMU to bump the fuel pressure and then fine tune it with the wideband and safc.

 

do you have an adjustable fuel pressure regulator? Are you set on stock pressure? I know my pressure is turned back to compensate for my 370's. But I know with JWT you are suposed to be running stock pressure. I am sure you have already thought of this but just thought I would throw it out.

 

Way to go JWT! I see they are still producing top notch work. Have you contacted them about this yet?

 

At that level of power, the 555's should be more than sufficient. With a proper tune, no need for an FMU. It just looks like the JWT is jacked up. And for the dyno operator to make a full pass with the A/F's looking like that is irresponsible. At no point was the A/F safe, yet he continued to run it.

 

I have gotten results like that, where the afr from the tail pipe sniffer indicates leanness for a range of rpm. My wideband data didn't match what the tail pipe sensor was indicating, however, and the power didn't drop. This indicated an exhaust leak somewhere after the wideband sensor that pulls in fresh air at certain rpm, such as with a standing wave situation where the negative pressure is at a joint in the exhaust system.

In your case, however, you do get a drop in torque that corresponds to the rise in afr, indicating that either the mixture is indeed going lean, or perhaps you are getting some misfiring over that rpm range. Misfiring will result in unreacted oxygen that the O2 sensor detects and produces a false lean measurement.

I had misfiring problems after going to the 2.87" pulley, but it was all above 6500 rpm. It is pretty unlikely you would have misfiring in the mid-rpm range and at the limited amount of boost pressure you are making.

Just thinking out loud here.

 

A few things to consider.

It would be premature to start saying the JWT program is bad. Didn't you buy that ECU from a member who has been known to be shaddy..... the same guy who ripped off Neal on a TS ECU that turned out to be stock?

Have you gotten the injectors flow tested?

Also, like stated before the wide band could be giving a false reading.

Last time I was at the dyno I had at the bung where the wide band o2 sensor was screwed in and I got a false lean reading. Opened the cut out and stuck the o2 sensor up into the down pipe and got a correct reading

My JWT ECU AFR's are fine, and so are most other JWT programs. It is the timing that is a issue with their ECU's, not AFR's.

Also, if you could post those graphs with RPM instead of speed that would be nice.

 

Yes I did get them from a shady guy but i found this out after from neal. Neal and i were talking last night and we came to a conclusion that if that was my real a/f then i shoulda blown my engine on my first boosted run, and considering since ive gotten the instalation ive done about lets say 20+ full boost runs without any problems at all. But mike thanks for the input and here are the graphs as requested.

 

Well what I said was I would think you should've popped something with an AFR like that. Maybe because you are running so little boost it just hasn't occurred yet. I would still think you'd have some symptoms you'd notice though. I notice slight misfires that only persist for a second or two.

The best thing at this point is to avoid boosting until you have your own wideband so you can check the AFR yourself, further upstream.

 

Yeah I need a wideband realy bad, will get one sometime this week or order one anways and wait for it to get here. Today later on ill put it on a lift and go over everything with soapy water, for leaks.

 

Just because your afr was a bit leaner than we would like doesn't mean your engine was detonating. It might have been running a bit hotter than otherwise, but JWT ignition timing no doubt kept detonation suppressed.

 

That's a good point, I get detonation with better AFRs than that, but I've also got much more advanced ignition timing that a JWT ECU does.

 

MiP-Looks good man. Do you have any leaks in the system at all? How has everything been holding up otherwise?

 

Sorry to hear about Your ECU man. Hopefully its a real JWT. I have the 370cc inj with the jwt ecu and 3in pulley and im running a base FPR of 51psi. The ecu is for the 370cc and z32 but i didnt like the AFR i was gettin around mid 13s, so i then proceeded to turn up the pressure to 51 in which now I get an AFR in the low 12's, which is where i like it. This though was done with a tail pipe sniffer.