Misfire/driveability issues

[nissans13240sx]

To start it is a 93 ka24de with sr t25. I have a AFC, 370cc injectors, and a n60 maxima maf. I just swapped the MAF and 370s over yesterday to get rid of my FMU. It seemed to be running ok last night(a little rich) but today it is running like complete crap. It is misfiring but I pulled each injector plug and each made a drop in rpm. My timing is not set 100% I have been playing with the distribitor to see if that fixes it but it hasnt. Any ideas would be appreciated, its late and im tired of working on this already just want to drive it.

[Chris28]

Are you running any sort of tune at all? You can't put in 370's and a larger maf and expect them to compensate for eachother. You need to get it tuned.

Put your 270's and stock maf back in, as well as the FMU.

If you are running a tune, I apologize. Check your plugs. What do they look like?

[WDRacing]

Are you running any sort of tune at all? You can't put in 370's and a larger maf and expect them to compensate for eachother. You need to get it tuned.

Put your 270's and stock maf back in, as well as the FMU.

If you are running a tune, I apologize. Check your plugs. What do they look like?

He said he's using a AFC, thats airflow controller. It edits the maf signal going to the ecu to control the injectors.

To start it is a 93 ka24de with sr t25. I have a AFC, 370cc injectors, and a n60 maxima maf. I just swapped the MAF and 370s over yesterday to get rid of my FMU. It seemed to be running ok last night(a little rich) but today it is running like complete crap. It is misfiring but I pulled each injector plug and each made a drop in rpm. My timing is not set 100% I have been playing with the distribitor to see if that fixes it but it hasnt. Any ideas would be appreciated, its late and im tired of working on this already just want to drive it.

Do you have a wideband? You can't tune a AFC without one. If it's running like crap then you probably fouled your plugs. A car will idle and run at 10:1 AFR but eventually you'll fill your oil with unburnt gas as well as foul the plugs.

Not having your timing set is a problem in itself.

The FMU is a better option then the AFC IMO. Also, what are you using for timing retard on boost? I don't recommend running full base timing especially with the AFC. It advances your timing even more then stock since the airflow signals are altered.

In short, sell the AFC and use the FMU or buy a rom tune. All after you get the timing set correctly.

WD

[nissans13240sx]

Im going to weld in my bung today for the wideband and get that working. I will clean my plugs and regap them and see what happens. The only reason my timing isnt set anymore is because it wont idle so its hard to tell what degree its at.

My friend made a rom tune using a 90 stanza ecu. He tuned it for the 370s and rb20 maf(same as n60 I think?) It runs with that ecu but like crap. If i cant get it working ill swap my 270s back in and get a new fmu. I think the FMU I have now is to large a ratio. Thanks for all the suggestions, any more would be appreciated.

[nissans13240sx]

LOL well it ended up being something really simple. I had my afc set 3in 5out. I was doing some research last night and I guess alot of people use 1in 1out. I switched mine over its idling at about 14.5 a/f. Now I just need to do some fine tuning threw the rpms.

I cleaned and regapped all my plugs to .32, also set my timing to 15 btdc.

[WDRacing]

Good deal, let us know how it turns out after some fine tuning

[motoman399]

i was under the impression that you could use the n60 maf and 370cc's with no problem. is this not true?

[nissans13240sx]

i was under the impression that you could use the n60 maf and 370cc's with no problem. is this not true?

Yeah, I dont think thats true. It may run but it will be really rich.

[DevilMB3017]

i was under the impression that you could use the n60 maf and 370cc's with no problem. is this not true?

This has been suggested a million times.

And no one has ever proved it works, at all.

[motoman399]

This has been suggested a million times.

And no one has ever proved it works, at all.

well today i just picked up a set of sr 370's and im going to go to the junk yard soon to get a n60 and then its on im going to try it. although i dont have a wide band a/f but at least i can see if it will run ok. im not turbo yet either. so ya ill keep you posted in a week or so.

[nissans13240sx]

Well I did some tuning this weekend. Its running pretty good right now. I need to recirculate my bov it destroys my a/f on decel. Its a greddy type s and i have the spring set pretty soft. Also have to redo my oil return line I think its backing up. I'm going to get it dyno'd this week to see what kind of numbers I put down at 7psi, possible turn it up to 10psi.

[nissans13240sx]

LOL well.... I drove it about 70 miles over the weekend and as stated before it had no major problems. I let it sit yesterday because I had no time to work on it. Today I start it up and its misfiring and smoking again. Seems to be coming from number one cylinder. I have spark, im thinking I either have a leaky injector or a bad one. Good thing I have like 100 spare injectors, but so much for getting it dyno'd tomorrow Oh well still lovin the KA-T