2500 RPM Rev Problem

supra1008

supra1008

Active Member
May 2, 2007
1,179
0
36
Philadelphia
Hello all,

Need some help. If anyone can shine some light on the situation. I finally got my 1jz wired up. It starts and sound really nice! The only thing now is that I'll shift into first gear and it will start moving. It won't go past 2500 rpm. You won't hear the engine anymore. As soon as you let go of the gas pedal, the engine cuts back on. If I shift before it hits 2500 rpm, there is no problem. But then what's the point of the twin turbo when the turbos only kick in at least 3500 rpm. The engine light isn't on. Anyone know what's wrong with my baby?? I want to drive it with the top off before the summers over. Thanks a lot guys. You've been helpful in my other situations.

Chris.:1zhelp:
 
OneJoeZee

OneJoeZee

Retired Post Whore
Mar 30, 2005
5,721
0
0
38
aboard the Argama
My car was doing the same thing last time I installed my harness. It turned out two connectors were switched. The connector for the hydro fan ECU and another connector(can't remmeber which one exactly) are identical. And when switched, the fan would not run on high and car would not rev past 2500 or whatever RPM it was. Switched them and everything was ok. There's only one other connector in there that's the same as the fan one so it should be easy to spot.

Yes, it sounds trivial but you should check just to make sure...
 
S

Satan

Supramania Contributor
Mar 31, 2005
1,594
0
36
Tampa
Yeah.... this is a commonn issue with the 1JZ swap, but the answers/solutions seem varied.

Which two connectors are U talkin' about OneJoeZee? I have a friend who's inherited my old 1J and is having this issue. We were going to try and find a fan ecu to plug in near the boddy/ecu connectors.

Are you saying that the connectors he should be looking for would be near where the hydrofan woulda been (it's now on a US 2JZ TT waterpump).

Thanx,
E
 
supra1008

supra1008

Active Member
May 2, 2007
1,179
0
36
Philadelphia
Yes. this is correct the 1jz doesn't have a MAF... It has a MAP. I checked all the timing, I checked all the wiring and everything is working properly. I had to change to of the fuel injectors because the would stay open.

When I floor it in neutral, it does the same thing... It will cut out at around 2500 rpm. then when you let go it comes back on.

Finally I couln't figure it out so I opened up the ECU and checked it out. It turns out there is a burned circuit inside and a capacitor that is bad. So I ordered another ECU. I'm still waiting for it to come in the mail.

If it still desn't work. I'll check the two connectors that you're talking about.
Thanks everyone. You're a big help.
 
R

ReQuieM

malicious.com.au
Oct 14, 2006
270
0
0
Melbourne, Australia
www.malicious.com.au
If your hitting 2500 ish and then it drops then revs etc, so it sounds like your tapping the throttle, then its the plugs on the coil packs. Mine started to do it recently. One of the connections isn't nice and it is dropping a cylinder. When the ECU picks it up it goes into 'WHOA what the fk is going on??' mode. which means you can't get it past 2.5kish that and I found if you opened the throttle too far it would to the same.

Just order in some new plugs (just the plastic outsides) and replace! :)

HTH
 
supra1008

supra1008

Active Member
May 2, 2007
1,179
0
36
Philadelphia
I just installed brand new NGK Plat tipped plugs. I checked the plugs and they look good.

Yea I'll definately fix the ECU, but I got a good deal on another ECU, so now I'll have a back up ecu.
 
supra1008

supra1008

Active Member
May 2, 2007
1,179
0
36
Philadelphia
I got the ECU in the mail on tuesday. It is now installed. My car still won't rev past 2500rpm. I'm checking the connectors that onejoezee was talking about. Any more ideas?

Chris.
 
The Reaper

The Reaper

Single, and lovin' it!!
Jan 10, 2006
1,909
0
0
Florida
try checking the coil packs. mine does it with the ECU that i tried to get fixed. got it back and its still doing it. i put a diff ecu and it runs flawlessly.

i know mine is the ECU
 
supra1008

supra1008

Active Member
May 2, 2007
1,179
0
36
Philadelphia
What about the fuel rail? Has anyone checked that? The engine sits for so long... not just when you're putting it into the car, but the time before you get it. The fuel rail and/or injectors can get clogged up. right? I sprayed fuel manually with a spray bottle and and it revved fine until I couldn't spray fast enough. What do you think?
 
aphxero

aphxero

New Member
Jul 4, 2006
787
0
0
Seattle, WA
its on the tps.

You can kind of trick it if you want just run 12v to it. your idle will be higher but it'll probably solve your revving problem. on toyota 4 wire tps it uses a trigger to put the ecu in "IDL mode" this circuit opens when you crack the throttle producing 12v. That tells the ecu it's okay to go by the 0-5v signal. This produces a more consistent idle by taking the tps out of the picture. Its also used to turn on the iacv. if you need to raise it after that you can always feed power to one of the ELS wires. Those are usually for idle up vsv and such. I'm sorry I don't have exact information on wire colors/operations as I've never seen a stock 1j ecu.

Its easy to find

gnd is usually brown this is continuous to ground or E2 sensor ground
thr is usually blue or white this is the 0-5v sweep
idl is usually red this should have 12v when throttle is 1% or more
VC is usually yellow this is always 5v and is shared with map sensor

They arent always this color but its simple enough to figure out. When ANY 4 wire tps car wont rev its the first thing I check.
 
You must log in or register to reply here.
Top Bottom