Super sluggish & Terrible mileage w/ A/C on??

[Fastball]

OK, I just got back from VA Beach road trip with family. Before we left I gave the SHO a good going over. I replaced alot of parts and tune up components, so now it runs with a serious loss of power, and my highway gas mileage dropped from almost 30mpg down to around 20mpg. Freakin' horrible! Runs real well w/o A/C running, except for a little miss @ around 3 grand.

Because I changed so much I am at total frustration as to what could be contributing to the mileage & power drop off. Any input would be greatly appreciated.

Here's a list of changes I made before I noticed the problem; Autolite double platnium plugs, (no oil in plug wells), AC Delco wires, Motorcraft fuel filter, cam position sensor, and I pulled the small shim from the A/C clutch, (it was a needed fix). I was also trying to get rid of some serious stumbling of the motor, which when I ran the codes came up Coil 2 ign failure. Tracked that down to the DIS module and replaced it. Codes then all came up clear,that problem was solved. After the DIS replacement, the engine had a noticiable miss with A/C on. Then my waterpump took a dump, (better before I left for vac. than while I was on my way), got it repaired the night before we left. That is when it really started running poor. Except for removing the belt on the compressor nothing was done to the A/C system. I spun the pulley when the belt was off and it spun freely. Not as nice as the alternator pulley, but it still spun well.

Bad DIS module?? Fuel filter on backwards?? I'll check that today. I know a lot of guys only run OEM plugs and wires, but I wouldn't think that would only be a problem when running A/C. I don't think I reset the idle after reconnecting the battery, could this screw up power w/ A/C? I'll also reset that today. I checked the MAF since I run a K&N, but it looked fine. It was running great just a couple of weeks ago until the DIS module started acting up. I have a lifetime warrenty on it and was thinking exchanging it.

Thanks for any input, this has given me a royal headache and bothered me the whole time I was on vacation!

Later,
Dave

 

[F-22 Raptor SHO]

does the car miss at all when you are under a light load? Like if you ease the clutch out a bit with the e brake on? Could be a bad or miss placed plug wire.

 

[TYSHO]

I had some pretty close experiences with my 92. I only managed 22.5mpg with the a/c on, all highway miles. I then notice power loss that kept getting worse, I even had the sluggish feel and hesitation. Around 3500 rpms, if I was just cruising [any gear], I'd get a boost of power out of nowhere, like an extra cylinder came to life. It was almost consistant with that very same rpm, although I'd have that happen during other rpms, sometimes 2 or 3 times in one gear. The problem ended up being my ignition coil pack and I never received one code from the computer.

 

[TYSHO]

does the car miss at all when you are under a light load? Like if you ease the clutch out a bit with the e brake on? Could be a bad or miss placed plug wire.

I will second that. In my 89, I had 2 spark plug wires become disconnected from the plugs, one hanging out by the exhaust manifold and the other just loose in the plugwell. I had the same results, but much more of a power loss than I experienced in the 92.

BTW, it took some hard shifting and aggressive driving for that to happen.

 

[Fastball]

She pulls out smoothly enough and I'm sure the wires are correct because I realized something wasn't right when I replaced them when following the wiring diagram in the Chilton manual. I found the correct diagram here on the Forum.

The miss isn't that huge around 3 grand, my wife can't feel it when she's in the car, but I sure know it's there. You know how it is when it's your baby and you drive it almost everyday.

Unless the coil pack just went bad, I doubt that's it because when I was trouble shooting the DIS last week the guy @ Autozone had one in stock to let me try it to see if it was the problem for the code 46 I got. It wasn't and they let me return it, then ordered the DIS module. It does start to pull stronger and alot better when the secondaries kick in. But I have to downshift to get that rpm range even @ highway speeds.

I just checked direction on fuel filter and loose connections of wires. Everything there is correct. I called the Ford dealer and he should be able to get me new OEM plugs by the end of the day. I'll change them out and take the Autolites back just for the sake of "process of elimination".

Dave

 

[TYSHO]

Let us know if it's the plugs.

 

[SHO#7]

Just a thought. But you said it got much worse after you water pump went bad. Did you dump a ton of coolant on the crank sensor. Maybe you are getting an erratic signal.

Also, on a side note. My 93 seems to lose alot when my AC is on. I don't have a miss or anything like that. Just seems like I lose alot of torque with the compressor running.

Mike

 

[Fastball]

No, really didn't make a mess with the coolant. Did find a mouse nest behind the top of the waterpump though, (I don't drive my SHO much during the winter, Subaru goes a lot better).

But that is what I am lacking, torque!

Dealer just called, plugs are in already. Man, they've gone up in price since the last set I bought. Oh well, at least I can get some $$$ returning the Autolites & I'm hoping it may solve the problem.

Dave

 

[Fastball]

Well, the OEM plugs have helped the miss that was present @ 3 grand. From here on out it's only Motorcraft plugs for my SHO!

I forgot about trying to re-set the idle, so I tried that yesterday and drove her to work. It seemed to help a little. So when I got home I went through the idle re-set again and took her for a spin. YeeeHaaa! That was it! I don't know what I did wrong the first time, but she's running like her old self now. I am really shocked at how poorly she ran without doing a simple idle re-set.

Now I can start playing with these new Traction T/A's!

Thanks for everyone's input, bigtime!

Dave

 

[onefastsho]

Idle Reset?

What is a idle reset.How do you do it?

 

[Fastball]

I have been told you should also turn on the headlight switch after you disconnect the battery & turn off the switch before you re-connect to the battery. Here is the procedure I found here on the Forum;

NOTE 1: The Ford owner's manual directs that the idle program be relearned following any service when the battery has been disconnected. To do this, it states that the engine should be started and allowed to idle for the (approximately) 70 seconds without touching the gas pedal. Adding the accessory loads ensures that the EEC and IAC valve can accommodate the additional air flow requirements and still maintain the programmed idle speed.

NOTE 2: It is preferable that the car be driven immediately after setting the idle programming. While driving, allow the coolant temperature to rise to the normal range and run the car through its entire performance range.

Idle Speed Program Reset Procedure
-----------------------------------------
1) Disconnect the negative battery terminal.
....Optionally, disconnect the keep alive memory (KAM) connector in the small
....wire also landed to the negative battery terminal.
2) Wait at least 30 seconds.
4) Reconnect the KAM connector or negative battery terminal.
5) Start engine normally (never press the gas pedal).
6) Allow the idle speed to settle for at least 30 seconds.
7) Within 70 seconds of starting the engine, concurrently apply all accessory loads.
....a) Climate control to MAX A/C.
....b) Headlight switch ON, brights ON.
....c) Turn steering wheel slowly ~1/4 turn side to side.
....d) Press brake pedal.
....e) ATX SHOs only: shifter to DRIVE.
8) Do not turn off engine for at least 5 minutes.

Copy this and store it in a file in your computer. Sorta like starting your own SHO manual from tidbits here on the Forum.

Dave