so my friend bought his first fc 88 gtu. engine is healthy, zero smoke starts right up. heres the problem I can ease into the throttle and go past 4000 rpm but once Im at WOT It just stumbles and doesnt go anywhere! Its drives perfectly fine with no hesitation until I try to WOT at 4k rpm

Things I've changed to try to improve-
Tps-from running s4
found a couple ripped vaccum lines so changed those
Cleaned the maf with cleaner and filter
changed leading coil -from running s5
The spark plug wires were ebay obx, I pulled them off and the tabs were broken inside the coils(I though this was the problem, broken wires) So I put some mazdatrix wires I had on my s5
Plugs are fairly new

Things I havent dont but thought of and will do tomorrow-
Secondary Injectors
grounds


Its still on smog pump and stock exhaust (except header)

Im waiting on my block off plates and gonna open the 6 port which is stuck shut but Its gonna be my track car so its rarely gonna be below 3500 rpm.

Any Input would be great!

 

Also forgot to mention the Oil pressure Is low

 

Deff clean all your grounds and inspect the secondary injector clips. 2 most common reasons for the 4k brick wall. Get back to us after you do this.

Did you adjust the TPS properly? (must do while engine is warmed up)

Is the oil pressure only low while idling?

 

Yea Tps Is adjusted properly and The oil pressure Is low while driving also. It reaches maybe 40 tops.

 

Also a problem with my 91 s5 The oil seals are gone, Tons of smoke when cold once warm Its fine. say Im WOT on the freeway or at the streets of willow or In the mountains the car doesn't bog or die down at all. Once my car Is doing any kind of donut or sliding It will do it for a little bit and then just die down.

It doesnt die or slowly go down, It just drops very harshly to idling rpms. Only when the car Is sideways or spining. 9k rpms straight line or turning no problem. any Ideas on that? I'm thinking maybe bad fuel pump? I have a rebuilt turbo2 waiting to be swapped In I'm just waiting for my Na to go out haha. Been running on blown oil seals for 3 months now! still going strong starts right up every time!

 

Afm, check it out. I had the same problem.

 

So I found a wire that seemed to be grouned on the brake proportioner valve. I re grounded it and the bogging stopped but now the oil pressure reads above 110 at all times. Then the 4 rpm wall came back.

 

find the ecu and follow the wiring loom out a little distance ,, find the 2 looms where all the earth wires spider together with a brass clamps and solder there yourself another couple of 15a wires
and earth other ends to ecu case

 

What you might have done is ground the wire that was connected to condenser at the end of the wire which was to be mounted to the body. If the condenser falls off and the remaining wire is grounded it will cause the needle of the oil gauge to spike. This is done for test purposes only as to surmise whether the gauge is working appropriately. If you ground this wire for a period of time you can probably say "sayonara" to the gauge as it might be ruined.

 

Well the wire was just stuffed in the brake proportion valve with no bolt or tape. Just exsposed wire tocuhing metal

 

Ok so a few updates.
The car only has the 4k wall when its at normal operating temp! When its cold the car goes through the gears smoothly.

The coils aren't the issue they have both been changed. I made three grounds. Directly from the negative terminal and it helped nothing except for slightly better idle.

I opened the stuck six port today and removed smog pump. Still bogs. Block off plate going on tomorrow and going to make a few grounds to the ecu.

Plugs are also getting changed tomorrow. Hopefully those do something about this but any other tips you guys have would be great.

 

It's the water temp sensor on the water pump most likely. I just fixed an FC with the same problem by replacing that.

 

Did u ever check Afm??

 

The afm has been changed from a running car and same result. I made a ground out of a 2 gauge wire I had, I grounded it to all the ground wires on the clip under the trailing coil. It made the idle alot better and everything is brighter in the car but same bogging.

Still haven't put the block off plate yet but going to tomorrow. Im also going to make some grounds going to the ecu. Also just put brand new plugs in

 

Try the water temp sensor...

 

hey, I too had that same issue.
I cleaned all grounds and checked my tps.
It also made my car idle better but shortly after that my alt went out.
once i replaced that (3rd gen) my car never bogged down at 3800 rpms ever again.
check it you never know.

 

Buddy finally got a day off of work so we are going to knock out every possible issue today hopefully! We have a bunch of wire and vaccum lines and new intake manifold gaskets.

Gonna re ground every ground with much better and cleaner points. Tear apart the intake manifold and fine any ripped lines and make a coupld grounds going to the actual rotor housing with the other ground that is already present.

I will be trying any ideas from this thread which I haven't tried yet and ill let you guys know how it goes!

 

Sp we changed the coolant temp sensor with an aftermarket brand from kragen, paid $25 with lifetime warrany. Its fixed the bogging for a day and a half. The bogging came back today. We r gonna get an oem one from a friend and see if its cause the aftermarket one already went out. If its not this then the last thing we have to try is the secondarys.

 

you have an 88,which needs the Aux port activation pipe,via the CAT.
you Deleted that right?..and put a Header there?(no split air pipe going to the aux ports any more)
So,I would look at that as WHY your Aux ports are not Activating and causing your car to fall on it's face.

 

The aux port are already opened up. My question is why did the coolant temp sensor stop the problem for about 1 day n a half.