sr20 won't rev over 4500 rpm.
 

Hey guys I'm stumped here. I have a red top sr20. It has a gt2781r turbo, 550cc fiveo injectors, z32 maf, and an enthalpy tuned ecu.
I had the turbo installed with a stock system before but I was experiencing fuel cut at 6k rpm. Now with the injectors, maf, and tune my car gets to 4500 rpm and backfires constantly and doesn't go any higher rpm.
So far I have sent my ecu back to enthalpy to verify my ecu was correct. Went through 2 sets of fuel injectors. Tried about 3 different mafs. Got new plugs. Ran a jumper wire from my speed sensor to the ecu in case the ecu wasn't registering my wheels were turning causing the launch control to activate. Checked for any vacuum leaks with carb cleaner and also a poor man's smoke test with a cigarette. I'm lost at what this could be.
The car idles fine, revs fine until 4500 rpm. I'm getting no codes on the ecu. Anyone have any ideas on what to check? I'm at a total loss.

Boost leak possible. Also what's you AFR at and is it only under load or dose it happen at
idle as well?

How far away is your MAF from the turbo?

If your MAF is too close to the inlet it will cause these issues.

Maf is in the same location it has been since it was stock. It doesn't have an air filter on it right now though. And it goes this at idle and under load. But the tune does have a 5k rpm launch control. My cheap tachometer could easily be off 500 rpm. To test it now I have jacked the car up and tried revving it in gear since the snow prevents me from being able to take it out of the garage. My fpr is also stock so it's not adjustable.

I vote for boost leak then.

You might have a leak in your piping, couplers, or your intercooler it self.

Also I verified my timing at 15 degrees. It doesn't appear to be smoking. I sprayed all coupling, hoses, and intake manifold gasket with carb cleaner with no change in idle.

You need to make something to hold air in the intercooler system. Carb cleaner never helped
Me find a leak.

Well that would explain a lot. I was also told from enthalpy that the speed sensor goes to the gauge cluster then to the ecu. The cluster itself changes the readings so making a jumper wire from the speed sensor to the ecu itself since I don't have a cluster won't work. Is there any way to bypass the cluster or something?

The gauge cluster changes the signal, if i remember correctly the sensor sends a sine waveform and the cluster changes it to a square signal.

You don't need the needle to work, just that converting part. Most speed'o healer systems can do that too.

I do have a cluster that doesn't work but it's been sitting in the back of my truck for the last 4 or 5 months. Would this item I need be water sensitive? Lol I don't have any kind of speedometer right now so this may possibly be my issue if I can't find a boost leak. Also is there a write up you know of that shows how to wire this up without the cluster itself?

Or would it be easiest if I just buy an aftermarket universal speedometer. Wire the speed sensor to the speedometer then the speedometer to the ecu?

It has nothing to do with "a speedometer", it has to do with the OEM cluster.

I have no launch control, but i do know you can drive these cars without the speedometer connected (that is one way to go over the speed limiter). I don't think the problem is there, unless it has to do with launch control not detecting you are moving - and it may detect you are moving based on speed info.

The first thing you could do is change the launch control setting. Or remove it.

If it were not for the launch control, and you could reach higher rpm without going much on boost, i'd say boost leak / problem with fuel delivery though.

Yeah I assume if the signal isn't getting to the ecu so the ecu isn't recognize I'm driving leaving the launch control active. I'm kind of on the limb whether or not to pay enthalpy to take this off or if there's another, possibly cheaper, or better way to keep the launch control and get it to work. While also looking at a better way to test for boost leaks other than soapy water. Granted before the tune injectors and maf the car worked well except for a fuel cut.

what spark plugs are you using and what is the gap setup at?

Plugs are new bk6re or something like that. Gapped at about .25

wrong plug, gap too big you're blowing out your spark.

gap your plugs to 0.7mm and make sure you use the copper plugs (BKR7E)

http://nissanraceshop.com/product/sr20det-spark-plug/

Hmm. I replaced the ones in it with the same plug. I'll make sure that it is the bk6. If it is then I'll get the bk7 gap them to .7 and try again.

Verified I got bkr6e plugs. I'll get new plugs in the morning. I also picked up a new fuel filter. I'll come back with results as soon as I find out.

make sure you are gaping at 0.7MM not 0.7" but from the sounds of it, since the turbo and boost level is all that changed, spark blowout seems very possible. are you able to free rev it past 4500? (light throttle)

Got an update. Replaced my fuel filter, got the correct spark plugs and gapped them. My old plugs didn't show any signs of rich or lean mixture. I am able to rev the car slowly and it stops instantly at 5k rpm. If I give it any more fuel it holds at 5k and just backfires. If I do it quick the tach just bounces between 4500 to 5k rpm and backfires. As of right now I have taken the ecu back to enthalpy to get the launch control taken off to verify that's not the issue.

Possible CAS issue?
Only saying cause my motor had similar issue with not revving past 4 or 5k and backfiring. Was CAS related for me. If your ran fine before upgrades then maybe not.

I just got my nistune upgraded with launch control. It is based on speed, so with a not working speed signal, it will limit all the time. I suggest you get a working speedo instead.

Sounds like the launch control to me, why not have it set to a switch activation instead of speed based?

Take off the launch control for the tune, worthless at 5k anyway. Also keep in mind it is damn cold up here, a lot of SRs do this when its this cold when the tunes aren't exactly right. Launch control on that small of a turbo is worthless. Plus if you are going to drag the car you need to set the 2step at least 7kRPM if not redline. These cars DO NOT need the OEM cluster in the car to run and drive fine, I've driven at least 2 mostly stock cars with the gauge cluster sitting on the workbench and had no issues. The correct plug is a 7, With that small of a turbo you aren't going to have blowout at .025, that should be fine.

Hey man this post was about 5 years ago but I’m having the same issue and I see you mentioned AFR. My Sr20det was running perfect with an intake stock (maf) untill I installed a Greddy intercooler ,my car wouldn’t rev past 4K I don’t have gauges or any idea of my afr
at the moment. But obviously my car has to be running more lean. Does that have anything to do.