The title says it all. I have a buddy who put on a TFS track heat on his 91 5.0 (stock long block, 65TB, 2.5" exhaust, ProM 75mm mass air and 24lb injectors) in preparation for a supercharger. The charger addition is about 2 months away, but he had to fix an oil leak at the back of the stock intake so thought about saving some time and putting on the TFS now. The problem is, when he punches it, the car will slightly stumble a few times up to 5500. It is a subtle stumble, but noticable. If he eases into full throttle, it will pull just fine up to 5500 with no stumble. It seems to be there the faster the car revs (not so much how high, but how fast it gets there if that makes sense). Went through the whole timing issue (set at 10*) and ignition (new cap and rotor, plugs wires check out, plugs check out, no noticeable or so far detectable vacuum leaks; EGR disconnected for years on the stock setup and no problems from that, same with smog equip.; fuel pressure set at 38-39psi (no vacuum). We have been going over this thing for 2 days and are totally stumped. Anything we missed?
What are the symptoms for too much intake?
- Thread starter 19stang67
- Start date
MrKwik
Founding Member
what he said.....I dont think it would cause a stumble. You got something else going on there.Marlboro_Man said:
the codes were 33 (both engine on and off), 44 (engine on) and 94 (engine on). An EGR (33) and 2 thermactor codes. It pulled these codes before with the stock intake and ran just fine with no issues for years.
I agree, i figured it would be sluggish out of the hole and pick some on the upper.
Where should I plug in a vacuum gauge to check the vacuum? I was going to use the one plugged port on the tree we moved over from the stock since it is an intake vacuum. I have only check on carbed cars before not on injected ones. I figure it would not jurt to have that data as well.
I agree, i figured it would be sluggish out of the hole and pick some on the upper.
Where should I plug in a vacuum gauge to check the vacuum? I was going to use the one plugged port on the tree we moved over from the stock since it is an intake vacuum. I have only check on carbed cars before not on injected ones. I figure it would not jurt to have that data as well.
backfocus
Member
You can plug into the tree with the vac gauge. Should be 17 to 22, if I remeber correctly. Someone posted, the other day about checking for an intake leak by disconnecting and pluging all the vacum lines to the intake, disconnecting the spark and turning over the enging checking for a leak that way. I have never tried this, but seems like a good plan. I will try to find that and post it, or you could search.
I had the same problem homey...
Turned out it was 2 things...
A) I had too little fuel pressure... 39 sounds perfect
B) I had a small vacuum leak
I've also seen a tune up cause this because of bad wires and/or bad cap
Turned out it was 2 things...
A) I had too little fuel pressure... 39 sounds perfect
B) I had a small vacuum leak
I've also seen a tune up cause this because of bad wires and/or bad cap
backfocus, post the vacuum thread if you find it. I am searching now but have not found it.
I am beginning to think this is something of an electrical gremlin. I remeber a while ago some people saying they cleaned a set of connectors by the intake and it fixed a few things. Would this be the ones that go into the fuel injection harness? What were they called? I was going to search this too to try it, but not sure what to call them.
I am beginning to think this is something of an electrical gremlin. I remeber a while ago some people saying they cleaned a set of connectors by the intake and it fixed a few things. Would this be the ones that go into the fuel injection harness? What were they called? I was going to search this too to try it, but not sure what to call them.
PS: I had an explorer upper and lower on a 1" spacer and a 70mm TB and I got mine to quit doing that... so there's no such thing as too much intake, it's getting the fuel to the correct mixture that counts, and I agree there's no need for 24lb injectors until the supercharger is put on.
You might want to check things like the control module, plugs, etc..
You might want to check things like the control module, plugs, etc..
backfocus
Member
The connectors are called the salt and pepper shakers, or so we call them here. They are right behind the intake on passenger side. Two big connectors one white one black.
I haven't found that post yet, still looking. Though I think hoodstrype has a point. It could be a plug wire, check them closely.
I haven't found that post yet, still looking. Though I think hoodstrype has a point. It could be a plug wire, check them closely.
backfocus
Member
88Stang331
New Member
- Mar 30, 2006
- 239
- 0
- 0
Just pretty much a loss of low end torque. And if you take a dyno tune before and after, your power band (peak power) should probably move up higher in the RPM range.
Vristang,
Maf (ProM 75 bullet) matched to injectors (ran fine with stock manifold), codes listed above. Just set a stock setting for timing. Have not tried to increase it, figured stock should be fine.
He just got back from lunch and one thing he said was that it did not act up all the time, but most of the time (say 80-90%). But there were a few times that he punched it and it had no stumble. He did notice one other thing. When he turned the car off, it would make a sound. The only way to describe it is like "air escaping inside a coffee can" Hey, his words not mine
. As best as he could figure, it sounded like it was in the upper plenum. I asked if it could be from somewhere else and he said it was most noticeable on the driver's side and sounded like it was coming from inside the plenum. I think it might be a small vacuum leak with that description. Any other thoughts??
Maf (ProM 75 bullet) matched to injectors (ran fine with stock manifold), codes listed above. Just set a stock setting for timing. Have not tried to increase it, figured stock should be fine.
He just got back from lunch and one thing he said was that it did not act up all the time, but most of the time (say 80-90%). But there were a few times that he punched it and it had no stumble. He did notice one other thing. When he turned the car off, it would make a sound. The only way to describe it is like "air escaping inside a coffee can" Hey, his words not mine
. As best as he could figure, it sounded like it was in the upper plenum. I asked if it could be from somewhere else and he said it was most noticeable on the driver's side and sounded like it was coming from inside the plenum. I think it might be a small vacuum leak with that description. Any other thoughts??
19stang67 said:Vristang,
Maf (ProM 75 bullet) matched to injectors (ran fine with stock manifold), codes listed above. Just set a stock setting for timing. Have not tried to increase it, figured stock should be fine.
He just got back from lunch and one thing he said was that it did not act up all the time, but most of the time (say 80-90%). But there were a few times that he punched it and it had no stumble. He did notice one other thing. When he turned the car off, it would make a sound. The only way to describe it is like "air escaping inside a coffee can" Hey, his words not mine
100% sure of a vacuum leak now- that's what mine sounded like. Re gasket the upper plenum or start the car and spray carb cleaner til it stops and then you found it
ok, sprayed carb cleaner ALL OVER the intake and had no changes in idle. Checked the vacuum with the car running and it pulls 17.5-18mmHg at idle. have not tried the vacuum check from Hissin50 yet (starting to rain so may have to wait till tomorrow). Could a vacuum leak be present between the runners of the upper and lower intake? Also, cannot tell anything is wrong with out engine at load under WOT. runs and sounds great till then. Will also check the spark plug cables again just to be sure, but i don't think that is it.
Man, carbed intakes are much easier to work with .
Man, carbed intakes are much easier to work with
.Carbs are for wimps!
A vac leak common to one of the runners in the lower intake and the lifter valley can be hard to find. When this happened to me I found it by excessive oil in the intake, and I actually had a vac signal from the crankcase.
jason
A vac leak common to one of the runners in the lower intake and the lifter valley can be hard to find. When this happened to me I found it by excessive oil in the intake, and I actually had a vac signal from the crankcase.
jason
MustangGT92
New Member
also try adjusting the throttle...it allows you to also adjust the air and fuel mixture....and increase your rpm's
vristang,
Ok, the only thing we could find is that on the rear runner (last one), we noticed some oil on the gasket when we pulled the upper intake off. I figured it came from the PCV vacuum line (we forgot to add the screen at first, duh-huh). the oil seemed to surround the port. We have another gasket on order. Could this be causing the leak? Would this be the upper to lower gasket or, please don't say a lower intake gasket?
Ok, the only thing we could find is that on the rear runner (last one), we noticed some oil on the gasket when we pulled the upper intake off. I figured it came from the PCV vacuum line (we forgot to add the screen at first, duh-huh). the oil seemed to surround the port. We have another gasket on order. Could this be causing the leak? Would this be the upper to lower gasket or, please don't say a lower intake gasket?
