Mechanical Gremlin :(

[mebcop]

Ok guys, I need some suggestions. I am having an issue all of a sudden that I'm trying to figure out.

If I'm driving along at say 40-60mph and I push in the clutch, the rpms slowly fall down to under idle (500-700rpms), and then either bounce UP to idle, or drop and the car stalls. I have had this issue before, and it was always that my filter on my crappy fitting JLT intake was coming off again, so I would disassemble the filter and reassemble it and the car would run perfect again for weeks/months. I have screwed with the filter a few times now since this has started happening, and it doesn't seem to be helping. Just tonight I wrapped my filter to tube joint with tape, and I am going to see if that helps on the way home from work in the a.m., but if it doesn't, I will need some suggestions???

I know it isn't in the tune, because this tune has run perfect before, and I also have my last tune that I ran all year last year, and that one does the same thing, so I know it's something mechanical.

I am starting with the wrapping of the filter-to-intake tube, to make sure that isn't the cause. Next I will wrap the coupler-to-intake and the coupler-to-TB and see if that helps. If neither of those help, what should I try next?

PS- If I just drive around town, it never dips below about 700'ish rpms and never stalls. It seems to be when I'm cruising for a while and then push in the clutch. My STFT's are within 2-3% across the board and my LTFT's are all 1.0's.

Thanks for any advice.

 

[mebcop]

Oh ya, I forgot to mention, if taping up the junctions doesn't work, I will be flashing the stock airbox tune back on the car and reinstalling it, just to see if it is intake related.

 

[pufferfish]

Check to make sure your MAF is as horizontal as possible. Improper clocking can cause idle recovery issues.

 

[mebcop]

Check to make sure your MAF is as horizontal as possible. Improper clocking can cause idle recovery issues.

I have the TVS JLT. You can't change the clocking of it. But Thanx man.

 

[califsp]

You sure the maf is clean?

 

[mebcop]

You sure the maf is clean?

Its funny you say that, I was just getting ready to go get some MAF cleaner.

I just did some more testing. I took the shroud off the filter to make sure it's not putting pressure on the intake pushing it causing leaks. If I stay in town and keep it under say 40mph, the idle is PERFECT. You push in the clutch and the idle drops right to 750 and stays within about 25rpms. But if I'm above 40mph, and I push in the clutch, it keeps varying from about 750-1000rpms. It'll drop to 750 for a couple seconds, then raise to 1000rpms for a couple seconds, then drop to about 800 for a couple seconds, then raise back to 1000 for a couple seconds, and then once I stop it'll settle back to about 750rpms.

 

[Blazer707@TBR]

Its funny you say that, I was just getting ready to go get some MAF cleaner.

I just did some more testing. I took the shroud off the filter to make sure it's not putting pressure on the intake pushing it causing leaks. If I stay in town and keep it under say 40mph, the idle is PERFECT. You push in the clutch and the idle drops right to 750 and stays within about 25rpms. But if I'm above 40mph, and I push in the clutch, it keeps varying from about 750-1000rpms. It'll drop to 750 for a couple seconds, then raise to 1000rpms for a couple seconds, then drop to about 800 for a couple seconds, then raise back to 1000 for a couple seconds, and then once I stop it'll settle back to about 750rpms.

Just pop your maf sensor out real quick and make sure there is not a small bug or leaf inside of it or something. I just installed a JLT on a TVS car and the shroud pushes very hard on the filter and I can see what everyone is talking about. But with a screw or 2 in there you shouldnt have a problem unless the rubber starts to rip on the filter.

 

[mebcop]

Thanx Blazer. I just sprayed it with cleaner and put everything back together. I didn't see anything in it but I didn't look real hard. I hadn't seen ur post before I did it. But I have a buddy in town with a whippled 5.0 so if its still doing it then I'll try his MAF sensor. Eliminate one thing at a time I guess.

 

[mebcop]

OK, I've been screwing with this stupid thing for a long time now...

I took the intake off, took the sensor out, and cleaned the sensor. I put it all back together and left for a couple hour tour. For the first hour and a half the car ran GREAT. I was excited, thinking FINALLY, I FIXED IT..... then, all of a sudden I push in the clutch at 55mph and it stalls. I got back up to 55-60mph a few more times and push in the clutch, and either it drops below 750 and then surges up, or it stalls. When it isn't idling down right, the rpm drop isn't smooth. It'll start dropping fast, slow down, then drop fast again.

So, last night when I got home, I called my buddy who has a 5.0. He drove over and we simply swapped the MAF sensors (didn't touch the intake at all). We went for a short ride, and I pushed in the clutch 4 different times at 55mph. 2 of the times the car stalled, 1 time it idled down right, and the last time it fluctuated from 500-1000rpms a few times as I was coasting.

So, the next thing we did was swap his whole JLT CF intake onto my car, and I can tell you, THEY DON'T FIT THE SAME AT ALL. With his intake on my car, the thing ran PERFECT. It idled down a lot slower than with my intake. My intake makes my car idle down really fast and then try to catch itself at idle. I mustve pushed in the clutch at 55mph about 20 times, and it never once even dropped below 750rpms at all. Even when mine is running at it's best, it drops to about 700rpms for a couple second and then raises up to 750.

I put my whole intake back on at this point, and the car ran decent again. It still drops to 700 and then raises back up to 750 almost every time, but it's not surging a ton or stalling.

It has to be something with my intake. With my intake, when I push in my clutch about 45'ish mph, it drops at different rates every time. Sometimes it drops really fast, and sometimes it's slower. With his intake, it idled down fairly slow (not too slow, perfect) every time the same.

I tried wrapping the intake tube to filter junction with electrical tape with a screw through the filter into the tube to keep the filter from moving, and the clamp over the screw, and the electrical tape around the outside. Now I am positive that it's not leaking at that junction, nor is the filter sliding off the tube anymore, but it's still doing it. I can't figure out what is causing this. I looked the tube over for cracks and I can't find any. The bypass valve port was easily wrapped in electrical tape too, to make sure that wasn't leaking, and it didn't change anything. There's no good way to wrap the PCV port, but it looks sealed. I know things change when the engine rocks, but I don't really know how to seal it for sure. When the car started running badly on my cruise, I checked and the coupler/clamps from the intake tube to the TB seemed like it hadn't moved at all.

I am LOST. I don't want to spend $450 to buy another intake, just to test it It ran perfect with my buddies intake, but it's not like I drove it for a couple hours either.

Any other suggestions???

Thanks for the help guys

 

[pufferfish]

i don't know what is different between your intake and your friend's intake, but i had an issue once with an SN95 mustang, where the filter was extended down in the fender well by a tube and it would stall just like that. then, i shortened the tube to bring it higher and the issue went away. i believe it was either air turbulence or too much air being blown directly onto the filter (possibly both issues).

if your intake still uses the fresh air tube that comes from the grill to the air box, try blocking it off or deflecting the air flow away from the filter and go for a spin to see if it effects anything. if it does, there's the issue. if not, i have no other suggestions. good luck!

 

[mebcop]

OK, I did a data log of when it stalled. The log shows something very interesting. The MAF frequency dips pretty hard in spots when it stalls, but when it doesn't stall the MAF frequency is very smooth. Air is bypassing the MAF sensor somehow (either turbulence or vacuum leak. I went through all my vacuum leak sources and nothing helped. I then put my friends intake back on and the stalling/dipping stopped. It HAS to be turbulence somehow. I don't know if over time I've clamped down too hard on the intake-filter junction (to try to keep the damn filter on) and curved the intake tube in or something. I will be getting a new intake next week and hopefully that fixes my issue. Let me know what you guys think.

 

[pufferfish]

have you tried to block off or deflect the fresh air tube from the grill? don't know if the roush grill was installed when the issues popped up, but that can add a lot of direct wind to the filter.

 

[mebcop]

I've had the saleen grill for a few years now. I drove all year last year with this exact setup. I def understand what you're saying though. I checked the fresh air tube and its secure and clear.

 

[hopony]

OK, I did a data log of when it stalled. The log shows something very interesting. The MAF frequency dips pretty hard in spots when it stalls, but when it doesn't stall the MAF frequency is very smooth. Air is bypassing the MAF sensor somehow (either turbulence or vacuum leak. I went through all my vacuum leak sources and nothing helped. I then put my friends intake back on and the stalling/dipping stopped. It HAS to be turbulence somehow. I don't know if over time I've clamped down too hard on the intake-filter junction (to try to keep the damn filter on) and curved the intake tube in or something. I will be getting a new intake next week and hopefully that fixes my issue. Let me know what you guys think.

You wouldn't have these problems if you had just bought a "wal-mart super charger", but seriously have you called JLT to see if they will swap yours out? I have not seen the jlt on a 5.0 tvs, but I have put a couple on 4.6 roush cars. I am not a big fan of the quality of that kit, but have had no problems with the one on my paxton.

 

[mebcop]

You wouldn't have these problems if you had just bought a "wal-mart super charger", but seriously have you called JLT to see if they will swap yours out? I have not seen the jlt on a 5.0 tvs, but I have put a couple on 4.6 roush cars. I am not a big fan of the quality of that kit, but have had no problems with the one on my paxton.

No, I would've spent the last week and a half "clocking" my MAF sensor back and forth... LOL. I hope people didn't really take offense to the wal-mart comment, it was just a joke.

I haven't called JLT, as I am done dealing with him. He just tells you that you don't know how to install a CAI. I don't need that right now. I will be purchasing the Roush CAI next week, no more screwing with this stupid intake. It's already damaged my car in a couple places.

 

[hopony]

No, I would've spent the last week and a half "clocking" my MAF sensor back and forth... LOL. I hope people didn't really take offense to the wal-mart comment, it was just a joke.

I haven't called JLT, as I am done dealing with him. He just tells you that you don't know how to install a CAI. I don't need that right now. I will be purchasing the Roush CAI next week, no more screwing with this stupid intake. It's already damaged my car in a couple places.

I thought it was a pretty funny comment. The Roush CAI would have to be better quality from what i have seen.

 

[bmyles]

I am in the same boat as you I ordered a roush cai a week ago , it sucks that you have to buy it but what else does a guy do.

 

[mebcop]

OK, something interesting. I was watching my fuel trims last night and they were crazy. When my car was tuned it held within 0-3% fuel trims (LTFT's stayed at 1.0) 99% of the time. Last night as I was driving down the road with cruise control on 60mph, and it would read between -16 and -19% for a mile or so and then it would swing to +15 to +19 for a while. Every so often it would come back to (-2) - (+2). Its like someone flips a switch and it flops from -16% to +16%. It'll stay on -16 to -19 for a mile or so(sometimes 4 or 5 miles even), then +16 to 19 for a while (sometimes a mile and sometimes like 5 miles).
I thought maybe it had to do with the evap valve opening with a leaking tube, so I shut the car off, unplugged the electrical harness so it would default closed and then started the car back up and drove it. That didn't change anything. I am still buying the roush intake but I'm worried it won't fix my problem.

 

[JUIC3D]

Sounds like an unmetered air leak (post maf)

Crack in the intake tube or coupler maybe

 

[mebcop]

Well, just a quick update. I put the roush stock-airbox lid on and flashed my old vmp tune for the stock airbox, and the fuel trims hold steady now. I've driven it about 250 miles now and the fuel trims were always within about 5%. I am fairly confident that my issue will be gone when I put the roush cai on when it arrives

BTW: If anyone is interested in a cheap JLT intake for the TVS, I'm sure it can be screwed with to make it work (longer coupler/sand filter-tube junction)... I'm just not going to take the time.