ronev

Hello folks,
I've searched the forums and found similar threads but not a solution so I hope I'm posting in the right spot. I have a 94 sc400 with 252k miles on it that wont rev past about 3800 or 4000 rpms. I've changed the plugs, wires, rotors, caps, ecu. and TPS. I've verified that the timing is lined up with the correct timing marks. I'm receiving codes for 24, 31, and 71 and have a MAF on the way to hopefully cure 24 and 31. The overdrive light will turn on and off with the button and appears to work out on the road. I can get it up to speed eventually but when the pedal is floored it will only rev to 3800-4000 rpms and then bog. As long as I don't floor it it will shift through the gears because the the shift points are below 4000. The "trac off" light is on. Both coils are working properly and my buddy is still twitching from an accidental close encounter with both coils. Will these three codes cause the ECU to go into limp mode? I wouldn't mind a few ideas on what to check and I hate the thought of taking it to the dealer. any thoughts?

SC4Paulo

iTrader: (2)

Sounds like MAF, chime back in when you get the new MAF in.

Dream36

The TRAC off light always comes on when check engine light is on. If the TRAC light in the tach comes in you have tranny related issues (in my case a bad tps). As far as revving, I agree maf could be suspect. Could you borrow a ECU from someone to eliminate that issue? When I replaced mine all the little problems went away.

ronev

So I pulled the car in the garage to change the MAF and it stalled and wouldnt start. I then had to push it the rest of the way in. It didnt start , so I changed the MAF and it still wont start. I paperclipped the fuelpump, loosened the fuel rail banjo bolt and turned the key on and it sprayed pretty good. I pulled a few sparkplug wires and turned it over and saw some spark. I suppose the next thing I will do is swap the original ECU back in and see if it will start. Whats weird is that I have spark, and fuel

ronev

I changed the MAF and cleaned the plugs. it idles fine, checked codes, i'm getting 24 and 71. The O/D light is continually flashing also. I'll swap back the original ECU and see if anything changes. Thanks for any help.

ronev

I put the original ECU back in, no codes, but its still in limp mode I suppose. it still wont rev above 4k, I took it to a local shop for them to diagnose.

ronev

I picked it up from the shop and though it idles better it still won't rev past 4k rpms. It still seems to lack power from a dead stop. It feels as though the rev limiter is kicking in, it revs up to 4k then drops back to 3700 or so. What would control or limit it, It doesn't seem to be fuel related but something the computer is cutting out. Does anyone have any ideas?

ronev

The shop I took it to said the MAF/IAT was giving odd readings from the oscope so i have another on order. they also said my fuel pressure regulator was putting out 8 psi too much, any idea what that will do?