Engine/Transmission (1994 - 1998) Clogged Catalytic Converter, or ?

[guldam]

Before I installed the #10 fuel plate, I noticed my 12valve didn't want to rev beyond about 2800 rpms, and now with the #10 plate it still doesn't want to rev beyond that. Is this a typical symptom of a clogged Catalytic Converter? The truck now has 184k miles and when I pulled the EGR it was all sooty, as was the grid heater. The truck still doesn't act like it got a 40hp and gobs of torque increase that the #10 plate should have given it. No other symptoms. No smoke. Runs smoothly.



No gauges yet. They are on the bench, as is a new fuel filter.



Cat or lack of fuel or ?



Guldam

 

[The patriot]

Before I installed the #10 fuel plate, I noticed my 12valve didn't want to rev beyond about 2800 rpms, and now with the #10 plate it still doesn't want to rev beyond that. Is this a typical symptom of a clogged Catalytic Converter? The truck now has 184k miles and when I pulled the EGR it was all sooty, as was the grid heater. The truck still doesn't act like it got a 40hp and gobs of torque increase that the #10 plate should have given it. No other symptoms. No smoke. Runs smoothly.

No gauges yet. They are on the bench, as is a new fuel filter.

Cat or lack of fuel or ?

Guldam

I'd pull the cat anyway.
Have you ever replaced the return line behind the filter housing?
Ever check out the fuel heater? Theyre prone to leak.
The little arm inside the housing that touches the cam plate is sometimes not touching the cam plate in the proper place, that will cost a lot of HP.
is it an auto or stick?

 

[guldam]

I've ordered a Cat test pipe... Will pull cat, install test pipe and see.



No, have not replaced the return line behind the filter housing. Will take a look at that over the weekend.



Fuel heater is sooty, but seems fine. But I've ordered new gaskets for intake horn. Old one was a bit funky, and I've fretted about air leak there.



I was thinking I'd pull the #10 plate out, and reinstall thinking maybe that arm wasn't in contact. Good reminder!



I seem to recall that the truck didn't want to rev before my mods. Was thinking on my maiden trip that the redline was silly since the truck wouldn't go beyond 3k.



Auto.



Thanks for the suggestions. Will take a look at all these things and more.



GulDam

I'd pull the cat anyway.

Have you ever replaced the return line behind the filter housing?

Ever check out the fuel heater? Theyre prone to leak.

The little arm inside the housing that touches the cam plate is sometimes not touching the cam plate in the proper place, that will cost a lot of HP.

is it an auto or stick?

 

[cerberusiam]

Sounds about right for the stock governed rpms. I think you need a governor spring upgrade.

 

[The patriot]

Sounds about right for the stock governed rpms. I think you need a governor spring upgrade.

Was thinking that. Mine will go to 3K or just a bit over but I have a 5 speed.

 

[The patriot]

Fuel heater is sooty, but seems fine. But I've ordered new gaskets for intake horn. Old one was a bit funky, and I've fretted about air leak there.



GulDam

I mean the fuel heater that's built into the primary filter. Down by the lift pump. Theyre prone to leak and show no sighs of leakage.

If all above mentioned is OK, I'd start thinking lift pump assuming all your filters have been changed. .

JM. 02

 

[guldam]

I was wondering about the governor and whether or not it would let you rev up to and beyond the 3k. Truck is slow to rev beyond 2400rpm. Perhaps that's a function of the #10 plate I'm going to pull and replace with a #6. What I want is a more usable powerband. Right now the sweet spot is just below 2k rpms and if I have the truck out of overdrive and am at the sweet spot in 2nd or 3rd gear it has plenty of power. But that sweet spot is very small. It's interesting to be moving along in 2nd gear with mild acceleration, then to suddenly shift to 3rd, and it starts pulling hard in that sweet spot.



I have to get the gauges installed pronto so I can see what the EGT and Boost is.



In the meantime I'm waiting for new intake horn gaskets, fuel pre-filter (3845400S), installing new fuel filter, Cat Tester Pipe etc.



The truck starts easy, runs smooth and has no smoke. Perhaps I'm looking for problems that don't exist.



GulDam

I mean the fuel heater that's built into the primary filter. Down by the lift pump. Theyre prone to leak and show no sighs of leakage.

If all above mentioned is OK, I'd start thinking lift pump assuming all your filters have been changed. .

JM. 02

 

[MLee]

while your taking the plate out to change it, screw the spring cap on the gov springs down one notch, on each. this will give you a little more rpm. and fuel. Side the afc cover forward, you might get more smoke than you want. If this is the case slide it back a skosh, and then adjust the smole wheel inside for less smoke or just a little. find that happy medium, to use the fuel. Check the plate to see if the toe was sliding under the plate. the little thing that ride up the plate for fuel.

 

[jtwcummins]

Put 3k gov springs in, you will rev to about 3200. Makes all the difference in the world. My 97 12v only reved to 2800 until the gov springs were installed.