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-   -   Can not rev past 4200 (http://legacygt.com/forums/showthread.php?t=201737)

dspl1236 02-15-2013 12:09 PM

Can not rev past 4200
 
96 ej22e

I know i have seen this issue on here before....but cant seem to find any fixes. I had a fuel line feed leak i thought he pressure drop might be the cause, replaced the line..no leaks..issue still there. Also at the same time I started to have idle issues. mpg's have dropped as well.

I have 1 code and its for my speedo. I had a code for coolant temp, but it went away when i cleared it. I have a new sensor in the box still.

I have a feeling my isv sticky/bad..but that wont cause what feel like a soft rev limit. My MAF is a reman and only 6-7 months old.

Any tips or things i should check?

dspl1236 02-15-2013 12:15 PM

This is under load wot or partial.

also my speedo worked for a second while taking hard left highway onramp...

Tr00b 02-15-2013 01:40 PM

Manual or auto?

Auto goes into limp if you have speedo code.

Manual I would check your MAFS and TPS.

dspl1236 02-15-2013 01:48 PM

Quote:

Originally Posted by Tr00b (Post 4295980)
Manual or auto?

Auto goes into limp if you have speedo code.

Manual I would check your MAFS and TPS.

Thanks. Its a 5speed. I bet its tps. But I'll clean my MAF to see how that goes.




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Riehl 02-15-2013 07:00 PM

Vehicle speed sensor. Done. Rev limiter comes on there?

spooln30 02-16-2013 03:27 AM

I would say it's gonna be your TPS sensor (throttle position sensor).

Sludgeroo 02-16-2013 06:52 AM

Hate to thread jack but how does this problem get straightened out with a MAP?

Just make sure vacc lines are not cracked and just check TPS as well?

Tr00b 02-16-2013 07:02 AM

Sludgeroo... Reading fail?

Sludgeroo 02-16-2013 12:45 PM

Quote:

Originally Posted by Tr00b (Post 4296751)
Sludgeroo... Reading fail?


No?

I don't have a MAF like everyone keeps telling me, its speed density.

Just wanted to know if these same issues could be straightened out with my car being speed density.

spooln30 02-16-2013 09:24 PM

^ So what engine and tuning set up do you have?

A bad MAF wouldn't even allow the engine to rev past 1500 let alone 4000 rpm.

Sludgeroo 02-17-2013 05:45 AM

Ej222 and its stock ecu, from what I was reading this was one of the only cars that had speed density this model year (99 Brighton ).

And I know that with a MAF on certain cars, the thing wont run barely unless the MAF is all good.

Like I said, I just have a loose understanding of the 2 systems and how it manipulates the air to fuel and then like you said, seems it would barely have anything to do with that.

Just from your experience, what are some protocols moreso that I can take to make sure a map/sd system is working optimal.

Sludgeroo 02-17-2013 05:47 AM

One thing with that, that is kind of peculiar is my friends miata. It was a MAF system until he went to a standalone with a Megasquirt 3 and that custom ecu required the use of a speed density system.

Aren't these systems supposed to be "inferior " to a MAF setup?

dspl1236 02-18-2013 10:39 AM

Just so you guys know... last night I was able to rev out to redline without my speedo. Also felt some power too. It has to be a tps issue. I snagged a tb from a junk yard.

Going to clean it up and toss it on today to see how it is.




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spooln30 02-19-2013 12:01 AM

Subarus TPS's have to be adjusted when installing. The use of a scan tool with data capabilities will do the trick. Key On Engine Off (KOEO) it should have a reading of .70 volts with your foot OFF the gas petal. Just installing the new one where the old one was will get you close but they need to be dead on for everything to work right. You'll need a better scan tool as most will only show TPS % and it's better to have the volt data. GL

Speed Density systems are some what better for turbo engines as the MAF sensors will create a flow issue to the turbo unless a larger higher flow rated MAF can be found for the application. Plus it's one less thing you don't have to worry about fabing some piping to and from and it looks cleaner w/o them.
What they lack verse a MAF sensor is the ability to compensate for temp and elevation changes accurately. A MAF sensor measures the air flow in real time and can adjust where SD can only make changes from the preprogrammed values.
I ran a MAF Translator in my old Supra, which is a tuning system that changes from MAF to SD. The biggest headache was when I tuned it in spring it got warmer and more humid it would run like crap so I would have to retune it. Then again weather changed I would have to retune it. Being a piggyback system was a downfall in itself. Most standalone ECUs like AEM or Pro-Efi are better suited for using a SD system.

Sludgeroo 02-19-2013 05:08 AM

Ahhh I see, thanks for that, as no one wanted to take the time to explain it to me.

That's why my buddy's miata has like 3 IATS and he has them averaged out at the different points in the engine bay so Megasquirt can recognize more realistic temps with that logarithm.

Obv from what you said it wouldn't be as accurate as MAF since the no air/density mixtures can bs the MAF since it has to go through it before being used for combustion.


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