SHO Drivability question

[Pat K.]

Hi All,

My name is Patrick, just joined the forum today. I'm a new SHO owner, but have owned several Mustangs so I'm fairly familiar with Fords.

I don't wanna give you guys a bad opinion of me asking a question in my first post, but I'm tired after working on my SHO all day and I'm about ready to pull my hair out.

I bought my SHO about 2 weeks ago for $1500, it's a 91' with 117,000 miles on it. It was running a bit rough and was lacking power when I bought it, so I decided the minute I got it home I'd check it out. I pulled one of the spark plugs wires off on the front of the engine to discover the plug well over half full with oil, enough oil to almost cover the top of the spark plug. I then began pulling the other 2 wires off only to find oil in those also.

Well I started looking around at websites on any info I could find on SHOs and lucked up on SHOtimes and read about plugs, wires, and the plug well seals. Knowing then what I needed to do to fix this, I started gathering parts. Even the local Ford dealers didn't stock the AGSP32PP plug so I ended up using the NGK PFR5G-11. I had to go with Carol 8mm plug wires from Autozone because that was all I could find without ordering them, and I needed to get the car running right as soon as I could. Grabbed the Felpro valve cover gasket set, and an intake gasket set as well.

Today I took on replacing the vavle cover gaskets, plug well seals, spark plugs, wires, and even replace the upper intake gasket to cover everything. Before I removed the plugs I was careful to soak up and remove all the oil from the plugs wells. I changed the plugs fast to try to ensure any residual oil didn't get down into the cylinder. I gapped the plugs @ .044. I also triple checked that I had everything plugged back in when I finished. When taking the car apart I found the electric solenoid on the back of the intake unplugged. I knew this was one problem.

Well, when I first cranked it up it purred like a kitten. I let it run for a little bit then took it out for a test drive. The car had TWICE the power it had before, and seemed to run perfect. When hitting the gas quickly then letting off fast, it would rev up to around 2300 rpms. (This is a test friends and I used on Mustangs to check throttle response.)

When I got back home the car pulled the driveway better than it ever has (I have a very steep driveway), then I let it run for a minute and warm completly up. When the car's temp got close to half way on the guage (normal operating temp) it started to idle rough again. Doing the same test I mentioned before (the throttle) it would only rev to around 1650 rpms. I went out and drove it again, got on it a couple times and it didn't have as much power. When I got back home this time it didn't pull the drive well this time, (like before the tune up.)

I let the car cool off and cranked it again. It idles smooth this time, and has good throttle response. Upon warming back up it start running rough again.

Does anyone have any ideas where to look for this problem? It's almost as if when it the computer comes out of cold start mode it starts running rough.

Any help at all would be greatly appriciated!!

Thanks,

 

[NotSoSlowSHO]

Welcome to the forum thumbs_u

And unfortunately (as well as fortunately... depends on how you look at it wink ) you seem like your elbows deep into the ownership of an SHO

First thing I would recommend is to find the correct spark plugs and possibly wires. I am not familiar with the wires ou have now. But time and time again motorcraft plugs have proven to be the only ticket on these engines. Using the [SEARCH] feature of the SHOforum will show a lot of discussions about the importance of the correct plugs.

Second, I would recommend you pull the EEC codes. They should give you a few clues as to what exactly is going on... remember, clue... not the answer

SHOtimes has a nice writeup on pulling codes but Mikey has a better one :

http://www.midwestsho.com/codes.html

 

[Porod]

Autozone will also pull the codes for you for free. I had to buy the motorcraft plugs at the Ford Stealer (dealer), as no other auto parts store here carried them, although if you don't mind buying of the internet, there are a few spots, one of which may be a sponser here. Check the sponsor list, I think it is something like Ford Parts Network.

 

[olympic]

It sounds like you have a closed loop problem. Meaning one of the sensors that come online when the engine is warmed up is causing a problem. It could be the oxygen sensors, MAF, coolant temp sensor, etc.

At 117K the oxygen sensors are probably original and should be replaced. You can remove the MAF and gently clean the filaments with TB cleaner or brake cleaner. If that doesn't help, unplug the MAF and run the engine. If it runs better with the MAF unplugged, then the MAF is faulty and needs to be replaced(uncommon but not impossible)

But I agree with the above, pull the codes for clues. Being a Ford guy, you should be familiar with this. If not check out this site http://www.dalidesign.com/hbook/eectest.html

 

[AutoSHO]

I agree with everything that has been said so far. It sounds like it could be one of a few things (pulling the EEC codes will narrow it down). The first thing that came to mind was, since it is engine temperature dependant, that is could be the Engine Coolant Temperature sensor (ECT). This will typically throw a code if it is bad. Clean the MAF for sure, it takes 5 minutes and can make a world of difference. Alternately, if you or one of your friends has a 89-93 5.0 Mustang, they use the same MAF as the SHO (same calibration) and you could try swapping it with one of their's to see if that changed anything.
Good luck with it, sounds like it shouldn't be a very complicated fix.

One thing worth mentioning is that at 117K it is 3K from due for a New timing belt. It is a good idea to change the water pump, crank position sensor, and front main seal when you do the timing belt. If you want more info, either SHOtimes or a search in this forum for 60K Maintanence should yield a lot of information. One last question, in 1991 there was a "plus" option package. Does your car have a fiberglass hood and a spoiler on the trunk? These are two clues that point to it being a plus model. The plus is typically worth a bit more in good shape (at least to a SHO knowledgeable person) and also a bit lighter. Have fun with the new SHO!

 

[Pat K.]

Thanks for all the input guys,

I have pulled codes with the key on engine off test, and got 11 - system pass.

It's been rather cold here lately, and I stayed out working on the SHO the other night to almost 10:00 pm in the driveway. So last night and today I've paid for it. I've come down with a really bad cold and can't get out there to do the engine running test.

Yes, the car is either a SHO plus, or has a SHO plus hood and trunk on it. Not sure if it was factory that way.

One thing I failed to mention, I have a rattle in my exhaust. The guy I bought the car from said it was just the cat converter shield. After reading alot in the forum last night, I see it could be a broken up cat. I need to run it down to Midas muffler and have them check. It also has flowmaster mufflers on it, if it matters. (I had flows' on my Mustangs, but on a SHO it makes them sound like a Honda .)

It almost acts like an ignition miss again. But I suppose if the car is running rich enough, which it seems to be, it could have already half gas fouled the plugs.

There was a tiny bit of residual oil left in the very bottem of the plug wells. Not even enough to get with a q-tip. - Didn't know if this could be a problem.

Also, the NGK PFR5G-11- Has anyone tried this plug? It's the right height. The spark plug boots seal the wells very well.

The car has had a water pump, timing belt and CPS put on it less than 5k miles ago. The water pump began to leak and killed the CPS the guy told me.

I really like this car and wanna get it running right. Also it's my daily driver.. so it's kinda a must do situation. It's still running much better than it was before the tune up. I did notice this morning when I cranked it cold that it's idle was rough... even cold now..

Thanks again for all the help, I'll get busy checking out everything you guys have suggested as soon as I'm able.

 

[AutoSHO]

If your cats are indeed bad, they may be the only problem. They may be plugged, and that would certainly cause the problem you are describing. If you are looking for a quick and easy fix, have midas cut out the cats and replace them with pipe. The best solution for performance is to order a SHO Shop or Performance Plus High Flow Y-pipe. The best bet, both for performance and the environment, is to get the Y-pipe with Catalytic Convertors.

Definately do the KOER test when you get to feeling better. If you can, check the fuel pressure also. It should be about 30 psi with the vacuum connected at idle and 39-42 psi with the vacuum disconnected and plugged to the FPR.

 

[Pat K.]

Ok,

Just ran the Engine running test, only got the following coeds:

74 - Brake on/off BOO switch action not detected during dynamic response portion of engine run self-test.

25 - Knock sensor signal not detected during engine run self-test. (dynamic response test)

The car definatly runs rough cold now too. Kinda makes me think the problem is ignition based. Could be the Autozone plug wires, or maybe the small amount of oil I didn't get out of the plug wells could be causing an arching problem..

Could the knock sensor being bad cause the car to run rough?


Thanks again for the help!

 

[AutoSHO]

Pat K.:
Ok,

Just ran the Engine running test, only got the following coeds:

74 - Brake on/off BOO switch action not detected during dynamic response portion of engine run self-test.

25 - Knock sensor signal not detected during engine run self-test. (dynamic response test)

The car definatly runs rough cold now too. Kinda makes me think the problem is ignition based. Could be the Autozone plug wires, or maybe the small amount of oil I didn't get out of the plug wells could be causing an arching problem..

Could the knock sensor being bad cause the car to run rough?


Thanks again for the help!

Those 2 codes are just from you running the test almost certainly. As the test is running, it will settle down and the check engine light will flash once. Turn the steering wheel side to side (at least 90 degrees each way), step on the brake pedal and release, and then do the "goose test", which is to put the pedal to the floor and rev the engine up, which tests the knock sensor. I have had the best luck with holding it in the WOT position for enough time so that the engine gets to about 4K rpms. When I don't hold it for as long I get the same code you do, for the KS.

Does the car run badly right at startup now also? Or is it only after it has had time to get up to temperature? Did you run the Cylinder Balance test? It might be a good idea to do so. If it is an ignition problem this will point you in the right direction.

 

[Pat K.]

Just done the cylinder balance test 3 times. Got system pass each time code 9

So here I am with it. No codes running or not, but a rough idle. So I guess my next step will be to have the exhaust checked and get some motorcraft plugs and wires to go in it


Thanks again for the help.