PLEASE HELP!!! No power after PI intake swap

laramik

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Okay so I have a couple different threads regarding replace my daughter's 98 mustang GT intake manifold because it was leaking. The car has 67,000 miles on it and is in pretty much tip top mechanical shape. Without going into too much detail I initially replaced it with a non pi aftermarket intake which leaked vacuum horribly so I decided to go ahead and do the pi intake swap. I purchased a genuine Ford racing performance intake manifold, the associated tube for the heat return a new water pump a new water pump nipple yada yada yada. Well it has been 24 hours now and the RTV has sealed. I took it out for a drive for about an hour today to make sure everything was on the up-and-up. The car feels like it has full power but only over like three and a half thousand RPMs. The car however feels like it is missing or even maybe running on 4 cylinders when under low throttle. I have check for vacuum leaks and there appear to be none. I have quadruple checked every single connector and they all seem to be plugged in. But to give you an idea, this car used to be able to burn rubber when I stomped on it in first gear and now I cannot make the tires even chirp unless I have the wheel all the way turn to the side and Hammer the hell out of the gas. I know I must be missing something but I cannot for the life of me figure out what it is. The car is throwing no codes and I even went so far as to verify that the check engine light does indeed work. I have a bluedriver obd scanner and nothing is coming up amiss. I have checked the oil and it is still clean so no sign of coolant in it. The only thing I can possibly think of is that when I very first started this project I forgot to disconnect the negative on the battery and one time sparked the positive from the alternator on a portion of the block. This just seems too much like I have a connector or a vacuum line not installed properly but I can't find one. The only thing I can see is that the vacuum line going from the back of the throttle body seems to be a bit corroded and cracking and with the use of a stethoscope I feel like maybe I'm hearing some hissing through it. However even if I disconnect it it runs the exact same so I don't really think it's that. I'm certain someone else's ran into this issue but I cannot for the life of me find anyone other than one guy with a crown Vic who seems to have had the same issue the car finally seems to have the appropriate amount of horsepower and torque and go but only after about 4,000 RPMs please please please help I have been working on this for 7 days straight due to ordering a crap NPI aftermarket intake that sucked. It's my 16 year old daughter's car which has recently got a new ball joints, struts, alignment, tires, convertible top, tie rods, brakes, brake bleed coolant flush and everything else that could possibly be wrong. Any help is most appreciated .. whatever testing you recommend I can more than likely do. I'm an ASE certified tech in brakes and undercar so I definitely know my way around a wrench. Please help.

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laramik

laramik

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One thing I forgot to add was that when I initially started the car I had forgotten to plug in the passenger side coolant sensor. I pulled over 3 blocks from home when I realized that the temp was like it was 0 degrees out. Saw on another forum someone having issues when the computer didn't think one of the sensors was plugged in.

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laramik

laramik

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Crap aftermarket detail had huge vacuum leaks even when torqued to spec. Removed and replaced with FRPP intake.

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Burninriverdiver

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You said when you disconnected the hose going to the throttle body it ran exactly the same and you hear some hissing? That sounds like the hose is the issue and extra air is entering the system whether the hose it plugged in or not. If you don't want to throw parts at it I would at least wrap the hose in electrical tape, plug it back in and see if it makes a difference. If it does, replace the hose.

I had a crack in that hose too, replaced it and it ran much better. I believe mine threw a lean code when it was cracked but it took a lot of driving for it to come on.

Wish I could help out more, keep us posted!
 

ttocs

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I thought the gains made in the pi swap were in the heads, not necessarily the intake. I might have forgot but I didn't think you did the heads?
 
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laramik

laramik

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@ttocs yes that is correct. I did double check all the plugs and wires to make sure they were installed in correct order and they are. I will tape up the one vacuum line running off the back side of the plenum to make sure its still good as that appears pretty dry rotted. I also reset the computer overnight by leaving the battery disconnected and will see if that makes a difference. One question, is it possible I could have switched the coolant sensors? Or are they the same sensor? Meaning maybe I put the driver's side one on the passenger side? Not sure maybe that could've happened but would that make this problem?

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ttocs

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if you suspect that your missing cylinders you can test it by using an infrared temp gun on the individual headers to see the temp difference. If you do not have one of those try disconnecting a plug at a time and see if it changes.

Also how did you check for vac leaks?
 
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laramik

laramik

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if you suspect that your missing cylinders you can test it by using an infrared temp gun on the individual headers to see the temp difference. If you do not have one of those try disconnecting a plug at a time and see if it changes.

Also how did you check for vac leaks?
I sprayed starter fluid all around the intake a bit at a time and no change in idle. I also vape so I used my vape and a straw as a sort of smoke tester and saw no visible leaks. It worked with the generic non pi intake actually quite well showing a leak at the front of the intake. That being said, I started it back up this am and it's actually worse. Seems like for sure I have a plug or two not firing. Wondering if possibly I fouled a plug with the non pi intake leaking coolant into either one of the plugs or into an intake port? Gonna grab a set of plugs now at parts store and guess I'll change the oil too although it's brand new synthetic mobile 1 but it shows nothing apparent on the dipstick to indicate coolant in the oil. Would it though if only a small amount got in?

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laramik

laramik

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I do have an infrared thermo that's a great idea!

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ttocs

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it was how I diagnosed my bad injectors. The headers towards the back will heat up a little faster then the fronts but they all should be pretty close. If they are off then pull and inspect the plugs and see what you have.
 

Silver95bird

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1. Blow out the spark plug wells with compressed air, and make sure you don't take a plug out first. Coolant in the cylinders is a big no-no.

2. A little dielectric grease on the boots/contacts does help. It's cheap insurance.

3. I've very rarely seen a 4.6 that fouled plugs irreparably. Clean them up after 1 and 2, and give it a shot. I'm big on autolite 764's and motorcraft coppers as well. Changed every 20-25k or so just as maintenance.

4. Pi intakes gain 12-15hp peak, and much more above that. Huge difference above 4k rpms. The pi cams are good for about the same, maybe 2-3 hp less. That leaves about 5-10hp max that the headswap is worth. Unless you have the engine out already, and don't mind the cost, or are dead set on the added compression, it's alot of work for little gain. It's not cost effective really, especially if you have done the intake/cam swap.
 

white95

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1. Blow out the spark plug wells with compressed air, and make sure you don't take a plug out first. Coolant in the cylinders is a big no-no.

2. A little dielectric grease on the boots/contacts does help. It's cheap insurance.

3. I've very rarely seen a 4.6 that fouled plugs irreparably. Clean them up after 1 and 2, and give it a shot. I'm big on autolite 764's and motorcraft coppers as well. Changed every 20-25k or so just as maintenance.

4. Pi intakes gain 12-15hp peak, and much more above that. Huge difference above 4k rpms. The pi cams are good for about the same, maybe 2-3 hp less. That leaves about 5-10hp max that the headswap is worth. Unless you have the engine out already, and don't mind the cost, or are dead set on the added compression, it's alot of work for little gain. It's not cost effective really, especially if you have done the intake/cam swap.

Best response!!
 
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laramik

laramik

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1. Blow out the spark plug wells with compressed air, and make sure you don't take a plug out first. Coolant in the cylinders is a big no-no.

2. A little dielectric grease on the boots/contacts does help. It's cheap insurance.

3. I've very rarely seen a 4.6 that fouled plugs irreparably. Clean them up after 1 and 2, and give it a shot. I'm big on autolite 764's and motorcraft coppers as well. Changed every 20-25k or so just as maintenance.

4. Pi intakes gain 12-15hp peak, and much more above that. Huge difference above 4k rpms. The pi cams are good for about the same, maybe 2-3 hp less. That leaves about 5-10hp max that the headswap is worth. Unless you have the engine out already, and don't mind the cost, or are dead set on the added compression, it's alot of work for little gain. It's not cost effective really, especially if you have done the intake/cam swap.
Alright. Just did this. Replaced all plugs with motorcraft ones while I was at it. Taped up the the hose on the back of plenum and it runs exact same. Actually the miss is maybe a bit more pronounced. Almost like it's running on 6 or 4 cylinders. I had my blue driver plugged in and ran all scans and comes up with nothing. Zero codes. No MIL. not certain what I can use in the live data to maybe track this down better. Took off plenum again today while doing all plugs and checked all connections and still nothing seems amiss. Was slight oil in intake under plenum but have brand new pcv in it now so don't think that's the problem. Any other advise would be appreciated. Could I have blown a coil pack? I did spill some trans fluid on to one but if unplug either pack car dies. Retested with spraying starter fluid all around intake still no change in idle like if vacuum leak was present. Help.

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Silver95bird

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Alright. Just did this. Replaced all plugs with motorcraft ones while I was at it. Taped up the the hose on the back of plenum and it runs exact same. Actually the miss is maybe a bit more pronounced. Almost like it's running on 6 or 4 cylinders. I had my blue driver plugged in and ran all scans and comes up with nothing. Zero codes. No MIL. not certain what I can use in the live data to maybe track this down better. Took off plenum again today while doing all plugs and checked all connections and still nothing seems amiss. Was slight oil in intake under plenum but have brand new pcv in it now so don't think that's the problem. Any other advise would be appreciated. Could I have blown a coil pack? I did spill some trans fluid on to one but if unplug either pack car dies. Retested with spraying starter fluid all around intake still no change in idle like if vacuum leak was present. Help.

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Stupid thought: unplug the maf and see if it changes. If you do and it magically runs better, then you have either a dirty/damaged maf or an air leak after the maf. If it runs just as badly or worse, then I'd look elsewhere. Bad gaskets around the iac, the TB, bad connections at the hoses in the intake tube, all can have a big effect.

Don't forget the ground wire on the engine harness to the fuel rail. Crumbling hoses on the evap system - fuel just rots them all. Been there done that. Then the pcv hoses, egr hoses, etc. Bad Egr valve gasket. Loose connection at the harness or on one of the injectors or coils.

Just trying to think of anything that might come undone in an intake swap.

Did any of the plugs look sooty or different from the other 6-7?

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laramik

laramik

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Stupid thought: unplug the maf and see if it changes. If you do and it magically runs better, then you have either a dirty/damaged maf or an air leak after the maf. If it runs just as badly or worse, then I'd look elsewhere. Bad gaskets around the iac, the TB, bad connections at the hoses in the intake tube, all can have a big effect.

Don't forget the ground wire on the engine harness to the fuel rail. Crumbling hoses on the evap system - fuel just rots them all. Been there done that. Then the pcv hoses, egr hoses, etc. Bad Egr valve gasket. Loose connection at the harness or on one of the injectors or coils.

Just trying to think of anything that might come undone in an intake swap.

Did any of the plugs look sooty or different from the other 6-7?

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None looked sooty. Plug 4 and 5 we're slightly dirtier than the rest. I did try the unplugging of maf iac and every other one . None seem to have any real effect except idle control and the coil packs. Maf and iac turn on mil as well as EGR plug turn on mil. I am suspecting vacuum at this point. The vacuum line at the back of the throttle to tle body is caving in to a degree but doesn't seem to change if I hold it open. However at full throttle it feels strong like all is good.

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laramik

laramik

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All seemed to be around 380 but I couldn't get to the rear two on the passenger side without taking off the plenum to measure them.

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lwarrior1016

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Did you go over all your connections and make sure they are all tight? How about going through the coil packs and making sure that you have the wires arranged correctly? Having a couple plug wires swapped could be an issue. Also make sure all your injectors are plugged in good.
 
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laramik

laramik

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Did you go over all your connections and make sure they are all tight? How about going through the coil packs and making sure that you have the wires arranged correctly? Having a couple plug wires swapped could be an issue. Also make sure all your injectors are plugged in good.
I did do all of this. Unless I have an injector plug out of order then it should be fine but each one lines up with where it was and wires are stick factory and numbered as are could so hard to mess that part up.

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