no power at 4 grand (cat now clean)

[nxk2000]

I’m having trouble with an 89 tgp. No matter what gear I’m in it will not rev above 4000 rpm. It holds steady around 4000 but acts like it looses all power. Once I back off the gas it will down shift and start accelerating again. Under a load the rpm will hold steady at 4000. In neutral it goes to 3500 rpm and drops 500 rpm to hunt between 3000 and 3500. One problem that I have for sure is a bad crossover pipe. I have check fuel pressure it is good. I have checked the exhaust back pressure. That is if I can get a good reading with the bad crossover pipe. It is reading about 1.5 psi at 2500 rpm. The O2 is reading fine. Tps is good. Map reading good. The plugs, wires, and maybe the coils have been changed. No check engine light. Thanks for any help.

[dbtk2]

There is a rev limiter and neutral and that is what you are seeing when you are trying to rev it. It is supposed to be 3k, but I have found it to be about 3200 or so.

 

Do you know how much boost the car is getting? The factory gauge sucks, but is that reading any boost? If you have an aftermarket boost gauge, what does that read.

 

Shawn

[skalor]

There is a rev limiter at 3000 rpms on park/neutral, and tachs tend not to be too accurate so no need to worry about that.

 

My first TGP did the same thing, it wouldn't rev over about 4000 rpms in gear. It turns out that the catalytic converter broke apart on the inside and a piece of it was blocking the exit.

[nxk2000]

The converter is now clean. It was braking down on the front half and somewhat plug on the back. It made a small difference. Is their a rev limiter while driving? It now acts more like it does in neutral. The speed will hold steady say in first gear at 30 mph but the rpm now jumps up and down from 3000 to 3500. Once again if you let off the gas for an up shift it takes off until the 3500 rpm mark. A new problem started now also. The check engine light came on with a code 33. Map voltage to high. Now during acceleration it bucks and surges to gain speed. But still has its problem at 3500. The map sensor is showing .98 volts at idle and when it starts to surge it jumps to 3.14 consistently. The dummy boost gauge on the dash shows about 3 to 5. For some reason the previous owner wired tied the waste gate arm. I did not get a difference when I removed the wire tie.

[Jeff M]

Horribly strapped for time but at least replied to your email. In short this problem has been stated before in the past and the pipe was the problem, and a replacement pipe took care of the problem. Your o2 readings help confirm this as the problem. So until you get things fixed, easy on the tranny

 

Jeff M