Stuu... stuuuut... stutter

[masho95]

Ok recently I've been having a problem with my SHO. I only seem to experience the problem when the car is cold and it first starts up. If you start the car cold and try to take off in first, there is VERY little power. It seems to just bog then finally will get going. I've only noticed it at part throttle and I'm not sure if it does it at WOT (don't think it does). Does it in 1st gear and 2nd gear. As soon as the car warms up a little it acts completely normal.

I showed the problem to one of our mechanics at work and he seemed to think it was ignition related (like a misfire). The car has new Motorcraft wires and brand new Autolite 3923 plugs (nitrous). I made two very short 3rd gear nitrous injections on the new plugs but haven't had time to look at the plugs. Our mechanic suggested replacing one plug at a time to find if it's just one bad one. (easy for the fronts )

I was thinking it was a bad sensor that's only used at startup with a cold engine (is that closed or open loop?) I know it's time for a new MAF, the one in there is slightly bow'ed out from the backfire I had a little while ago (see Emergency Issues post I made a little while ago). Also there is one wire that is slightly bent. So I'll have to look into replacing that sometime soon.

So anyone have any ideas?

 

[oh_SHO]

Does if feel like a misfire or just a lack of power?

 

[AutoSHO]

Mine does the same thing on cooler mornings. Try replacing the ECT.

Every SHO I've owned does it.

 

[masho95]

Let's see... also forgot to note that sometimes while trying to get it to go you can sometimes hear a little pop. I couldn't tell what it was, but the mechanic riding with me said it was a backfire. I think I'll try the ECT anyways, as it's the original sensor with over 104K on it now.

 

[masho95]

Anyone else? Well I bought a new ECT sensor which is going to be changed out tomorrow morning. We'll see how it acts after that. There's 104K miles on the stock O2's so I think it's about time to change them too. I think those will get changed out after the next paycheck too.

 

[revhardSHO]

Anyone else? Well I bought a new ECT sensor which is going to be changed out tomorrow morning. We'll see how it acts after that. There's 104K miles on the stock O2's so I think it's about time to change them too. I think those will get changed out after the next paycheck too.

Yup new 02s are a good idea. Is the engine throwing any codes?
Do you know if it did it before you changed in the nitrous plugs?

 

[masho95]

Yup new 02s are a good idea. Is the engine throwing any codes?
Do you know if it did it before you changed in the nitrous plugs?

It seemed to stutter everyone once in a while before even after warming up before, at part throttle. That was a random occurance and nothing like it's doing now. Like I said before I made 2 very short nitrous shots to see if it was working. Time to check the plugs I guess. I find it hard to believe that after 2 small shots that it'd be causing the car to run like that when cold, but you never know.

OH, and BTW I checked to see if it was doing it at WOT when the stuttering was happening and it didn't seem to bog at all. But maybe it's still a little slower than it should be. I'll see what's going on with the plugs tomorrow and I'll swap out that ECT while I'm at it.

 

[masho95]

Well I changed out the ECT sensor today, with NO noticable difference in the problem that I've been having. The plugs also seemed to be fine after two quick nitrous injections. Here are pictures of the plugs.

Also any input on how rich my car might be running from this picture of the tail pipe? I'm not sure how it compares to everyone else's SHO and any bit of input would help. Picture of the tailpipe.

 

[SHO--ripper]

Eric is there any black gunk around the intake? Mabye you need to tighten the clamps on the intake connectors. An intake leak will case a backfire.

 

[MilTownSHO]

Mine does the same thing ever since I changed MAF's, just an idea!

 

[masho95]

Intake seems to be sealed well sho--ripper. Went through all the clamps yesterday actually to double check they were all tight and they were.

Yeah the MAF is going to be swapped out next. I'll see if I can get a picture up of what happened to it soon.

 

[masho95]

Here are two pictures of the MAF that's in the car now. You can tell from the first picture that the filaments are slightly bowed out.

MAF pic 1
MAF pic 2

 

[masho95]

Ok I swapped out the MAF with a different one and the same exact problem still exists. I wonder if the colder spark plugs are making a difference? Like maybe they need to warm up for a minute or two before completely working correctly. I'd be more than willing to bet now that if I changed out the plugs with stock ones the problem would be gone.

Anyone running colder plugs ever have anything like this happen?

 

[SteedaSVT]

mine does the same thing

Changed plugs, Wires, Fuel filter, Tps, Dis, Coil, and its exactly the same ohh and 3 different maf's Its either not enough fuel pressure, Back injector or bad o2 sensors is the only thing that i can think of left

 

[SHO--ripper]

When i had my N20 89 i didn't have any problems with the autolite coppers.
Any way you blew a hole in a vac line with the N20 explosion?

 

[oh_SHO]

Have you gotten to check fuel pressure? Mine has a similar problem that I am almost positive is a fuel problem. I hope to be getting my hands on fuel pressure tester soon.

 

[AutoSHO]

With the 190 lph pump, I doubt he's having any fuel pressure issues, aside from some high-vacuum pressure overrun.

 

[oh_SHO]

With the 190 lph pump, I doubt he's having any fuel pressure issues, aside from some high-vacuum pressure overrun.

I doubt it too but it's better to cover all the bases...

 

[Marccus]

I had this stuttering, loss of power starting from 1st gear from a stop, backfiring, etc. for several years and I couldn't figure it out even with all the postings made on this board.

Finally, one day, the car wouldn't start at all and died at Pep Boys. They figured it was the fuel pump and I had them replace it. Still wouldn't start. Next, I replaced the IRCM figuring the pump relay circuit was bad in this control unit. After sleeping for two days in my car in the Pep Boys parking lot and receiving the new unit from a Ford dealer in some other part of the country, I replaced the IRCM and she started right up.

I've never had a stuttering, loss or lack of power, backfiring problem again and she runs fine. Perhaps I ddin't need a new fuel pump, but with 285,000 miles on the pump, it was probably a good idea to replace it. I just wish I hadn't paid Pep Boys $300 or so dollars to replace that part and I had done it MYSELF

Moral of the story - don't wait for the car to die if it is acting up. Find the problem and correct it. Although I tried to get a solution to this, no posting on this board could help me. Hopefully, this one can help you before you end up stuck somewhere.



1989 SHO with 289,000 miles (essentially stock) with high flow cats.

 

[SteedaSVT]

Wheres the Imrc located i looked in my chilton manual and can't find it. Someone tell me where it is?