No power under load

[sling]

I have a 1990 SHO that I bought a couple years back. The car ran great up until I decided to do a tune-up and discovered oil in the plug wells. Long story short I did an upper 60k. It has never run the same. Starts and idles great... revs fine but once I start driving the car is very sluggish. Engine sounds good the whole time though. Secondaries open and all.
I pulled codes earlier today:
KOEO - 21
KOER - 24
26
77
Then I unhooked the battery to reset the codes and drove around for a while and the only code I pulled after several attempts was 11, and the cylinder test was good as well.
I have replaced:
TPS
O2 sensors
fuel filter

I suspected the cats and so I unhooked one of the O2 sensors and took it for a drive, but I did not notice any difference

 

[SHObogdan1]

Code 21: Engine Coolant Temperature (ECT) sensor out of range - ECT

-It's possible that your engine wasn't up to normal temperature yet when you did the test. Check to see if your radiator fans work when the engine warms up. A bad ECT sensor would stop your radiator fans from turning on. But most likely, the engine wasn't fully warmed up yet when you did the test.

Code 24: IAT sensor out of range

-If your IAT sensor is bad, then your engine will run leaner, you'll definitely need to replace this to make your car run right.
http://www.autozone.com/autozone/re...ending-Units-and-Sensors/_/P-0900c1528027923b
This link will show you exactly where the IAT is at, just incase you need it for reference.

Code 26: MAF out of range
-If your MAF is bad then this will also cause your car to run sluggish. Try taking off the MAF and cleaning, it should help, otherwise that'll need to be replaced. Oh, also try unplugging the MAF and see if the car runs any better. If it does, then the MAF is definitely bad.

Code 77: System did not receive goose test
-I think that you get this code because you're supposed to step on the gas pedal during the KOER test after the CEL flashes three time. So that one can be ignored.

The description really sounds like you have faulty MAF and IAT sensor, those will definitely cause your engine to run very sluggishly.

I hope this helps, let me know.

 

[sling]

Thanks for the quick response and the code symptom explanation. I was looking at replacing those sensors but shouldn't the codes be logged again after some more driving? I probably put another 20 miles on it seeing if it would relog those codes.
I also was looking at the plug wires and found one that I think may be faulty. It wasn't properly set and the wire pulled free of the boot. So I suppose that could be part of the problem.
I was going to take a trip to the parts store and I will go ahead and get those other sensors and install them if that is warranted from the codes I pulled earlier today.
So in reference to my question above, is that first batch of codes still valid since I was unable to pull them again?

 

[SHObogdan1]

I think that if you had a bad spark plug wire, you would get a noticeable misfire. As for the CEL light not coming on, that's not unusual. Those codes will still stay stored despite the light not being on, and it may take a long time before the codes reappear again. Typically a bad MAF coupled with a bad IAT sensor that would cause your engine to run sluggishly and give you problems. The best anecdotal advice I have is with my 98 Lincoln Navigator. Granted, I know it is a different car, but when the MAF went bad, it was having the same symptoms as your car. I remember that it idled fine but it had no power under load and didn't rev past 2000 rpm no matter how hard you would push the gas pedal. After I replaced the MAF, everything was back to normal and the car ran great.

 

[sling]

Sounds good... Purchased the parts and will keep you updated. Again, I appreciate the quick response.

 

[sling]

So I installed the MAF and the IAT, but there was barely any difference. Still running terrible. Idle is good still, but as soon as I begin to let off the clutch it wants to die. I have to give it a lot of gas to keep it going. I wonder if I didn't put everything back together just right during the 60k, because even when there was oil in the wells it still was running great. This dogging didn't begin until I had completed the work. Would a vacuum leak cause these types of symptoms?

 

[Irish Pride]

Retrace your steps and double check everything you did. If it ran fine before you did the valve cover gaskets then it must be something unplugged. Look for any loose plugs dangling. My first guess going by the symptoms would be the TPS is unplugged.

Double check your plug wire routing. That gets messed up all the time.

Engine -
1 2 3
4 5 6

Coil pack -
5 1
6 2
4 3

 

[SHObogdan1]

+1 on the plug wire routing, other than that, a vacuum leak could be possible. Did you clean the mating surfaces really well when you removed the intake manifold? When I finished the upper 60k last June, I definitely had a vacuum leak on my '93 ATX but it was galloping at idle and it was hesitating under full throttle. I had to take the intake manifold off again and brush all the dirt of with a scotch-brite pad until both surfaces were 100% clean, that finally fixed my vacuum leak.

 

[rubydist]

did the codes go away when you changed those sensors? in my experience, a "iat sensor out of range" is almost always a wiring issue, not a sensor issue, but the engine will not run right with that code.

when you "did the upper 60k" what did you replace?

 

[Shovert]

Only advice I can give is if it is vac leak. My engine ran like crude after removing the intake. I used this thing I built to find boost leaks. [2.3 turbo I have]. Set pressure to 10psi MAX. Hook to throttle body. It will show up vac/air leaks immediately. Maurice
http://www.vfaq.com/mods/ICtester.html

 

[sling]

Thanks for the input. I checked the plug wire routing and it is correct. I don't see anything unplugged and I have not been able to find a vacuum leak. I bought a compression tester and hooked it up where the first O2 sensor goes and tested for backpressure and I had to really throttle up to get the needle to move so I think that completely rules out the converters. Is that a correct assumption?
I just ran codes again and got 21, 26, and 92. I don't know how valid they are since I hadn't hooked up the front O2 sensor
I changed the MAF yesterday so I'm not sure why it's still throwing that code, but I haven't yet changed the ECT.

 

[sling]

RubyDist-
I followed the 60k guide on the shopheonix website and replaced all the valve cover seals, intake manifold gasket, plugs and wires.
One thing that I have wondered is whether I was supposed to put some sort of sealant on the manifold gasket.

 

[Irish Pride]

You dont put any sealant on the manifold gasket but you do need to make sure you have clean mating surfaces. Its very easy to get a leak if you do not have all the manifolds bolts tight. Just one not all the way can cause a leak but i dont see that being your problem.

 

[SHObogdan1]

You won't need to change ECT sensor (unless your fans don't turn on when the engine is hot), the car should be at operating temperature before you start the KOER test, otherwise you'll get that code.

As for the intake manifold, I'm sure others here have gotten away without using gasket sealant, as long as the mating surfaces are TOTALLY 110% clean. Even some minor specs of gunk will affect the seal between the intake manifold. Since the manifold is made out of aluminum, it's really unforgiving when not thoroughly cleaning it. Personally when I did the upper 60k, I used sandpaper and scraped every speck of dirt off for at least an hour and then applied a layer of gasket sealant underneath and overtop of both intake manifold gaskets. I was sure happy I did because I would've hated to start over again just to fix the vacuum leak.

 

[sling]

Sounds like there is nothing left to do but to remove the intake manifold and reseat it. I'll begin working on that in the next couple of days. Thanks for all the input. I will also check all the plugs and wires while I am in there.

 

[Irish Pride]

Typically, you can reuse the manifold gaskets over and over. What i do and what others do is to clean the gaskets really well and then right before you install them give them a coat of fresh spray paint. Then put the gaskets on and install the intake while the paint is still wet. This will help give it a better seal. You really dont want any sealant oozing out the sides disrupting air flow.

 

[SHObogdan1]

I never had any problems with gasket sealant oozing out and "disrupting air flow" if you use thin layers, in fact, it's actually recommended at corners and edges, especially since the intake gaskets aren't rubber so I don't really see how it would hurt.

 

[rubydist]

ok, so are you still getting codes? if so, what are they now?

the iat out of range MUST be solved for the car to run right.

 

[SHObogdan1]

Were you able to re-seat the intake manifold? Did the vacuum leak problems go away?

 

[sho'noff]

:deadhorse: