swapped explorer intake on, runs rich/bogs, please help!

[v8only]

OK, Anthony Dalyrmple and I worked on the mustang/explorer motor all day.

history: 86 mustang gt, 97 gt40p explorer engine, speed density, stock HO mustang cam, ported explorer intake, 65mm throttle body.

ripped off the ported stock intake and put on the ported gt40/explorer intake. In addition, I upgraded from a 60mm throttle body setup to a 65mm throttle body and spacer setup. Everything else remained the same.

Install went fine.

car runs and seems to idle fine, but you hit the throttle and it goes BLAH and bogs or dies bigtime. TPS set ok.(.96 volt) idle air motor good. manifold vacuum very steady 17-18 inches (speed density stock ho cam), timing 10 btdc,computer codes don't point to anything, no vacuum leaks. It's running rich as hell. While not as bad as the first time if you remember my old thread, but rich enough to make our eyes burn. (first time it billowed black smoke months back)
sometimes it will suddenly idle high and then die eventually.

any ideas?

 

[OrLackThereof]

Well its a little hard to say, Im used to a mass air motor....but you know that SD motors have a very hard time countering modifications and tend to require chip reflashes to run perfectly?

Cant see why you'd run pig-rich and have problems.....you have a lot of vacuum, which points away from vacuum leaks....as well as being rich, vacuum leaks would make you lean...but the MAP sensor would see less vacuum and add fuel I assume... Not familiar with SD systems, but how is the vacuum line to the map sensor?

Speed-Density motors dont do so well with mods, being that they run off of tables that are meant for stock motors....once you add parts, the numbers change, but SD doesnt know that like an MAF system does.

You could try to "patch" it....as I would do for people that come to me......bump your timing from 10 to 12 or 13 degrees.....and up your idle to 800-900 rpms, and reset your TPS voltage as close as you can to .98. This can get rid of some of the stalling/hesitation.

 

[dragnazz5.0]

youre still fighting that thing jeremy? good lord, and i thought i had problems with my car. check what the tps is at wot. maybe its sending a wierd signal to the computer. also....have you just tried to drive it around and give the computer a chance to reset all the fuel trim tables? maybe its running off the old tables...or trying too at any rate...but realizes something aint right so its just dumping fuel.

thats really wierd....i cant stop thinking and going through all the things that would cause that problem and its tough. speed density is a pretty simple engine management strategy. what injectors are you running? are they the stock injectors or a newer style injector...they might be the wrong kind. id also try bumping the timing up and see how that works out. what about egr...is it hooked up and working properly (ie. closing when you put it to the wood)

 

[v8only]

I had a ported "stock" ho mustang intake on it a week ago, I was running fine with that. When I tried putting the explorer back on again, the problems came back, just not as bad as the first time.


tps is at .96, pretty close to .98. I'm going to convert to mass air, however there are a TON of people who swear that speed density will handle this just fine with the stock HO cam which I have.

 

[dragnazz5.0]

the speed density should handle it. yeah the ported explorer flows more than the ported ho intake but i wouldnt think it would cause problems like this. i wonder if there is a flaw in the intake or something. there isnt a rag or anything jammed into one of the intake runners is there? **** happens..maybe there is something in there. it just doesnt make sense to go from running fine to running like ass because of the intake. my only guess is that the computer needs to relearn all the fuel trim tables.

 

[jrichker]

Did the orange O2 heater wire get grounded like it should? It comes out of the engine wiring harness near the TB.

 

[tmoss]

more info on this thread - it acts up when you give it throttle, that may be because you don't have the MAP and fuel pressure regulator on dedicated lines to the intake plenum (they see a loss of vacuum much faster when comnbined with the line to the tree and brake vacuum booster) - DO THAT and see what happens. OIther than that, vacuum leak is the only thing that should affect things but your vacuum looks good.

My SD took to the new combo like it was stock - but I run dedicated lines.

 

[v8only]

more info on this thread - it acts up when you give it throttle, that may be because you don't have the MAP and fuel pressure regulator on dedicated lines to the intake plenum (they see a loss of vacuum much faster when comnbined with the line to the tree and brake vacuum booster) - DO THAT and see what happens. OIther than that, vacuum leak is the only thing that should affect things but your vacuum looks good.

My SD took to the new combo like it was stock - but I run dedicated lines.

fantastic suggestion. I had wondered that myself. Last night the map was connected to the tree, so I swapped that to straight vacuum, however currently the regulator is T'd straight off vacuum source, I wonder if that could effect it?

Did the orange O2 heater wire get grounded like it should? It comes out of the engine wiring harness near the TB.

the wire that comes out of the fat harness from the salt and pepper shakers right? that one is grounded to the back of the bell. Are there any other grounds?

Thanks for your help guys, this is a problem that has plagued me with this damn intake every time I swap it on.

 

[v8only]

Tom, Fantastic suggestion.

I went back out and pulled the map off (it was a loose hose I was using) and replaced it with a super tight hose straight to manifold.

I then went and pulled the other vacuum line off that T in the back, giving the regulator full access to that vacuum and fired it up. It "seems" to idle fairly fine, and rev good, and holds that all the way till it warms up. NO rich black smoke.


Problem is, that damn explorer intake doesn't have enough of the small size vacuum lines, hence the T for the tab/tad/egr and the regulator...not sure what to do for that. Can I run the tab/tad/egr off of the vacuum tree on the firewall?

Thanks for the suggestions so far, and I"ll keep u updated after another trip to autozone for more vacuum lines later.

 

[tmoss]

you can run the MAP and fuel pressure regulator off one dedicated hose I'd think.......

 

[jrichker]

I am going to make a rather dangerous assumption that you know how to check the codes and have already done so. The 86-88 car do not have a check engine light that works, so you have to use either a test lamp or voltmeter to observe the output. If you didn't get an 11 (system pass) on both the engine off and engine running code dumps, dump the codes again and post your results.

Think about what’s happening - what tells the engine that the throttle has suddenly been opened? With SD, cars, there is only the TPS and MAP sensor. Usually a dump of the codes would show code 22 (MAP/BARO sensor), code 53 or 63 (TPS sensor).

Since the TPS is the most likely problem source, start there.
The TPS sensor is a variable resistor like the volume control on most cheap radios. The carbon element can wear and cause a drop out spot in the output voltage. This confuses the computer because it expects to see a steady TPS voltage increase as the Throttle opens up.

Wire colors & functions:
Orange/white = 5 volt VREF from the computer
Dark Green/lt green = TPS output to computer
Black/white = Signal ground from computer

TPS troubleshooting steps:
1.) Use the Orange/white & Black white wires to verify the TPS has the correct 5 volts source from the computer.
2.) Use the Dark Green/lt green & Black/white wires to set the TPS base voltage. Try this... Currently there is some dispute about setting it at .99 volts being worth the effort, but anything less is probably OK. All you need is less than 1.0 volt at idle and more than 4.25 at Wide Open Throttle (WOT). You'll need a voltmeter with a 1 or 3 volt low scale to do the job.
3.) Use an analog voltmeter to check the voltage on the Dark Green/lt green & Black/white wires to make sure that it increases smoothly and doesn’t drop out or increase suddenly.

MAP sensor troubleshooting.

The MAP or BARO sensor is pretty much the same sensor for both Mass Air & Speed Density cars. The main difference is where it is connected. Mass Air cars vent it to the atmosphere, while Speed Density cars connect it to the intake manifold vacuum. Its purpose is to help set a baseline for the air/fuel mixture by sensing changes in barometric pressure. The MAP or BAP sensor puts out a 5 volt square wave that changes frequency with variations in atmospheric pressure. The base is 154 HZ at 29.92" of mercury - dry sunny day at sea level, about 68-72 degrees. You need an oscilloscope or frequency meter to measure it. There is no way you can use a common cheap voltmeter or DVM to accurately measure the output signal.

The MAP/BARO sensor is mounted on the firewall behind the upper manifold.

Baro or MAP test using frequency meter - run the test key on engine off. The noise from the ignition system will likely upset the frequency meter. I used a 10 x oscilloscope probe connected from the frequency meter to the MAP/BAP to reduce the jitter in the meter's readout.

If it is defective, your air/fuel ratio will be off and the car’s performance & emissions will suffer

Some basic checks you can make to be sure that the sensor is getting power & ground:
Note that all resistance tests must be done with power off. Measuring resistance with a circuit powered on will give false readings and possibly damage the meter.
Check the resistance between the black/white wire on the MAP/BARO sensor and then the black/white wire on the EGR and the same wire on the TPS. It should be less than 1 ohm. Next check the resistance between the black/white wire and the negative battery cable. It should be less than 1.5 ohm.

The following power on check requires you to turn the ignition switch to the Run position.
Use a DVM to check for 5 volts on the orange/white wire. If it is missing, look for +5 volts at the orange/white wire on the TPS or EGR sensors. Use the black/white wire for the ground for the DVM.

 

[v8only]

I did pull engine codes, and got a plethora of tab/tad/thermactor problems, which I expected due to it not being completely hooked up.

I'll pull codes again now that it seems to be running a little better, but before I go through that, and your other suggestions above, here is an interesting tidbit.

we did go through and fully check for leaks everywhere. sprayed it thoroughly and no bogs/changes in idle.

yet on first test drive today, brake pedal worked fine once, then stiff like there wasn't any vacuum at all.

this doesnt' make sense. the brake pedal worked absolutely fine with my last intake, yet doesn't with this one, yet no apparent vacuum leaks. Bad booster? not likely, ?? this one is interesting, yet leads to an obvious vacuum problem somewhere that is wreaking havoc.

 

[lxarlo]

is it just me or does it seem like a 65 vs a 60 mm tb and an upper and lower intake that flows wayy more than stock would require maybe a small bump in fuel pressure? i would probably put an adjustable fpr and bump it up a few (3 or so) psi then reset the computer and see where you stand. you stated before that it ran way better with full pressure with the vac line off.

 

[Lxstang306]

do u have a vanum leak any where never no might have a bad hose and dont now it.

 

[tmoss]

Yes, the vacuum booster on the brake could be failing - or you could have a leak in the lower from the lifter valley side, which a spray on the outside won't find. Plug the oil dipstick hole, plug the PCV hole, and then test for vacuum at the TB line connector at the oil fill tube at idle - vacuum means you've got a vacuum leak on the bottom side of the lower intake.

 

[32785stang]

my guess would be that the vacuum line to the fuel reg. isnt hooked up but you said you have good vacuum....

 

[Dachipsta]

Just a little something I ran into when I swapped my stock lower to a GT-40 explorer lower. I had to drill out and tap the boss on the #5 runner to install the ACT sensor that came out of the stock intake. If that sensor isnt wired up and working, I would imagine that could cause some serious air/fuel problems......Just a thought.

 

[v8only]

actually I did drill the intake for the act.

Here is a pic someone gave me for this setup.

FYI< I haven't used that stock mustang ho vacuum tree coming off the intake, I'm still using the explorer one.

additionally, this pic shows the pcv valve connected to two sources of vacuum on the intake, any idea why?

I'm going to pull that metal vacuum tree off my stock ho intake today and swap it onto the explorer intake, test the booster, and go through the tests that tmoss suggested. I'll post back.

If anyone knows about the pcv pic above that would be cool. right now I have it going into only one vacuum source

 

[tmoss]

You'll have to drill/tap a 3/8" NPT hole in the Explorer intake for the HO tree. 9/16" drill + 3/8" NPT tap. I did it to mine.

 

[v8only]

sweet, thanks for keeping up on this thread and that info, I'll save this for the weekend when I have a chance to go all the way through it. I'll report back then...Jeremy