I know of two people in my area with this swap. Both are having problems with the rev limit being at 5500. They are both using the ls harness on the complete swap with the LS (p75) ecu. Does anyone have any idea what could be causing this rev limit to be at 5500 instead of 7200(?) rpm?

 

should of used a PR4 ecu(obdI), using the p75(obdII) on that car usually causes alot of problems

 

No, it's OBD I. There is no way it would be a direct plug into a 94 if it was OBDII. The p75 ecu was made OBD I and II.

Please read this : https://honda-tech.com/zerothread?id=348096

and don't spread misinformation.

 

my fault man, i forgot that the p75 was made obdI and obdII

 

No problem

Anyone else?

 

are they getting a cel?

 

Not that I know of.

 

to the top

 

anyone?

 

ttt, still looking for an answer!

 

well I'm no expert but the ls ecu isn't going to have a 7200 rpm redline because it doesn't.

You need an ecu out of a car that had vtec and the 7200 rpm revlimit.

 

Huh?
I don't have VTEC, why would I want a VTEC ecu? I know the motor stops making power at like 6700-6800 but the redline should be 7200. Why wouldn't a 95 obd I ls ecu work properly in my car?? (p75A01)

 

So you are saying that these people are hitting a rev limiter at 5500 rpm's? That's very strange and I haven't encountered anyone with that problem before. Are they running modified ignition systems like an MSD or anything? I would suggest changing the ECU with another one to see if the problem goes away.

 

When I get home, I'll take my ecu out and let them try. They aren't running any modified ignition. Weird problem!

 

did you try using the ex harness? just leave all the v tec related plugs hanging. my friend with a 93 dx hatch with 95 LS used the ls harness and it kept throwing codes. swapped to dx harness and no more codes. just a suggestion.

 

I'll track down and EX harness to try that out.

Also, Could the Ignition Control Module in the distributer be causing these problems if it went bad?

 

The igniter won't cause a 5500 rpm rev limit. Try to IM Katman or Kenji and see if they have any ideas. I have not seen this before, but it sounds like an ECU/harness problem.

 

Funny you should say that, I've already spoken to kenji and he doesn't know.
Today we put an LS ecu in that we knew worked (we drove the car over!) and still had the problem. We now know for a fact that it is not and ECU problem. Someone told me the ignitor can go bad at certain RPM. Is this true?

 

I have never seen an igniter cause an rpm specific problem. They usually either work, or don't. Post when you find the answer to this one, I would really like to know what the cause was.

 

Hmm

Thanks for the reply...I'm still working on this problem.

 

The VTEC ECU will run shittier due to the lack of VTEC hardware and knock sensor on the LS motor. It will run way too rich because it will be in fail safe mode because of the multiple CELs it will have.

No way would I run the VTEC ECU for an LS.

As far as the problem goes, I've seen bad distributors cause a "lower rev limiter" problem as well as a fuel pump going out. The fuel pump is an easy swap, and used VTEC F.Ps are cheap and relatively easy to find.

Try the fuel pump if you can find a local cheap one. If that still doesn't fix it they might have a bad distibutor.

Have they checked all the grounds too?

 

bump. interesting post