[Muttstang89]

Hello Stangers, this is my first real post here so please bear with me.



Well, to start out this little Snoozefest, Ill give you a little back story. The stang was orignially an AOD car. The orignal motor went south on me so we were able to find a low mileage replacement that included everything for a T-5 swap. We performed the conversion with relatively little issues a couple years ago and the swap really woke this car up...for a little while. As usual the T-5 syncros went bad after a good bit of abuse but there is no suprise there.



After the engine and tranny swap, I started adding some bolt on parts, exhaust, gears, and such. I do not run any type of power adders yet. The reoccuring issue here has been that the car seems to only want to run right when it feels like it. Most days it runs like ass , it doesnt really seem like time of day or temp matters unless its extremely hot out. Some times I will go out, hop in the car and tear ass down the road like theres not tomorrow and the majority of the days it will barely get out of its own way. To trouble shoot the car I have been through base idle resets, sensor diagnostics ( measuring ouput votage from various sensors), replaced bad sensors, pulled codes, compression test, etc, and nothing seems to make any kind of lasting improvement on this thing. But on a side not will running in this condition and driving it like a grandma, it bested a consitant 14.23 down the 1320 with 373 gears and launching at idle and granny shifting, not to bad for a fat guys car.



So after christmas of this past year, I have added (Dont shoot me just yet, I know all about the barage of comments about to come) GT40 exploder intake, and a trickflow stage 1 cam. Impatience got the best of me. Now before anyone gets all bent out of shape about "why did you do that and not heads blah blah blah", I have aquired a set of GT40P's that need to be put on, just havent made it that far. Now after doing the cam and intake swap, I was extremely impressed at how much that made a difference over the stock stuff, the car ran like a bat out of hell for a few days, then it went back to the same ole shenanigans. I found two vacuum leaks and fixed those and it didnt make a big difference in the symptoms/problems that I am having. And since the issue was happening before, I dont think that the issue is with the swap, but I understand that it can compound the issue.



Recently the stock 75 amp alternator took a dump. Here is what is crazy, and I have a feeling I know why this happened but ill wait for some responses, When the alternator died, we had jumped the car a few times to get it back home. At this point, the car was only running on whatever charge the battery had, I would say at most 11v at max, and it ran like a scalded dog. I grabbed second and it was all over the place just roasting the tires, I was pretty freaking stoked about it especially since it was doing this on already warm tires from highway travel. Sadly this was short lived. So that leads me to here, Upgraded to a 3g alternator that I had on sitting on the shelf, which was much easier than the write ups make it seem, and the first time we fired the car up and took down the street to make sure everything was good, it ran like a beast again, pulling my face off. We stopped at the local convience store and shut the car off for a bit, cranked her back up to go home and it was back to just bumming around and didnt have any ass behind it. I just dont get it.



Sorry for the book here, so now for the setup and mods:



5.0 stock block and heads

Busted T-5 Tranny #2

GT40 explorer intake/ with stock TB and relocated air charge sensor

Trickflow stage 1 cam

Full exhaust, shorty heads, offroad x-pipe into 40 series and tail pipes

70 mm mass air meter - factory Cobra style housing

New MSD Streetfire Coil (wich helped any higher rpm breakup that was ocurring)

3G alternator upgrade with appropriate wiring

Aluminum drive shaft

373 gears



Again sorry for the book but its at least a good amount of info to go off of from the start.

Thanks for your time and any help is appreciated.

 

[1barzx3]

Any codes?? Components don't like being run at low voltage so I would start doing a lot of your basic checks. Check fuel pressure, timing things like that.

 

[Muttstang89]

Idle Vid Current state of running.
Stang idle trickflow stage 1 cam gt40 intake - YouTube

 

[Muttstang89]

Ill do another code check tomorrow just to be sure but the last time the only codes were for the smog sensors that are still plugged up so I dont get the constant check engine light. But ill check those again tomorrow and see whats up.

ON the low voltage deal, thats what i thought was weird, it ran like a champ with the alternator not putting out any charge and with the battery on low voltage, just didnt make any sense to me.

Thanks for the help man.

 

[arieso94z28]

Did you change the computer in the car? I would of took out the A9P (Auto Computer), and got a A9L (Manual Transmission) put it. Makes a big difference.

 

[Madspeed]

the a9p wouldnt cause those isdues unless its bad

 

[408foureye]

Try changing the TFI module. Check for clean ground wires, especially the one at the back of the block for the O2 sensors. Wouldn't hurt to replace the O2 sensors either. Main efi relay can also cause issues. You can try another ecm, but I doubt that's your issue. A9P ecm shouldn't care whether you have an AOD or T5.

 

[badbrad]

x2 on the a9p not causing any of his issues. period. tf, coil or pickup in the distributor. check those out. check grounds too, i.e. resistance building with heat

 

[Muttstang89]

Alright Guys, did some trouble shooting today, KOEO test initially produced no codes, at some point after testing things it threw a code 96, I verified this by running the test 3 imes and produced the same results. I checked the power to the fuel pump at the pink and black wire and while the car was running it held a steady 13.60 volts so the pump is getting the power it needs through that connector at least but I dont know if maybe the relay is starting to go.

I am still running the automatic computer, I havent pursued an A9L yet or been able to try one out. It was my understanding that there are a few differences in fuel curves and how the computer acts with retarding timing and such but there are plenty of people running the auto computers with the manual cars without any major issues.

I checked through the grounds when we did the 3g alternator swap, common chassis grounds look good plus we even added another 4 gauge ground wire from the common chassis ground to the block so it should be doing good at that spot. The Ground strap from the head to the firewall is in place and not frayed or anything, maybe i should add another O2 sensor ground somewhere?

Whats the best way to test the grounds, hooked up or test the wires individually?

KOER I got the usual codes for the smog 44 and 94 (thermactor R and L) and a 33 which I have the vacuum line to EGR unhooked but that was to see if the EGR was the issue, just havent hooked it back up yet.

I put a vacuum gauge on the car again while I was doing some test while the thing was running, and it started out pretty low around 10hg, as I was setting the timing back down from 14 to 10 degrees base timing I decided to see what the vacuum gauge read when Increased the timing at idle. I took it up to about 20 degrees base at idle listening for any abnormalities, and the idle sped up and evened out of course and the vacuum gauge read close to 18 hg.

I set the timing back to around 11 degrees and she ran a little smoother through the gears than it did at the start of the day but still doesnt have the ass it has when it wants to act right.

Back to another question, could the computer be in limp mode of some sort?


I Seriously appreciate you all helping me with all of this, I know these things can be a PIA to diagnose not seeing the vehicle.

 

[Muttstang89]

hey another symptom of this whole thing thats been happening since ive owned the car that comes and goes but here lately it has been every time i start the car, First start on a cold start (whether its cold, warm, or hot out) it starts then stumbles and then dies. Start it back up and it does the normal idle. Ive traded out the IAC a number of times between a few that i have and it pretty much stays the same, ive cleaned the plunger in them and such, But have yet to drop the coin on a brand new one. Anything else that would cause this issue you think?

 

[Micah_14]

How low are you running your gas tank to? Is your fuel filter clean, fuel pump too? If you are running you tank low sometimes and it's got trash at the bottom, it might act like that. Idk, just a suggestion.


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[Trey LePark]

70 mm mass air meter - factory Cobra style housing

Can you tell us more about the MAF. This is kinda generic sounding. Exactly what housing is it and what electronics are in this housing? Do you know anyone that has a bone stock 55 MM MAF that you can borrow and test this out?

It sounds like the computer is jumping in and out of modes. Everytime you disconnect the battery it runs great. Then the computer looks at what's been done and it runs like crap.

 

[Muttstang89]

Sorry it took so long to respond, been working and taking some time to test some things on this piece.

I do have the A9P computer as well.

1 - Yesterday, the first test of the last couple days was the Leak down - Checked my gauge on my fuel rail before starting and it read zero. I did 5 cycles before I tried to start it. Started it and it sputtered and died( like a bad IAC), I restarted it and it kinda sputtered a bit the idle went lower and surged up and down a bit then steady out to the usual junk. I let it run for a couple min and check the fuel pressure and it was reading a normal steady 35-38psi, with a quick WOT rev, the fuel pressure dips down into the 20's but rebounds back into the 30's as the vacuum comes back. I shut the car off and watched the gauge to see what happened, the pressure actually climbed to about 42psi with the car off, I let is sit for about 6 hours and rechecked, it was back to zero again.

2 - Today I went a little out of my mind, but I figured The only way to really know whats going on is to take stuff apart and see whats happening.
My cousin and I decided to drop the tank and check out the fuel pump to see if maybe there was some junk stuck in the sock filter or if maybe the sock filter itself was messed up. We pulled it all apart and everything looked like it should, It still has the factory Ford fuel pump, the hose had some surface cracks but nothing that looked to deep as to cause and issue, the sock filter was pretty clean, it had a little bit of junk on it but nothing major, but if it has been in the tank since 89 it was in pretty good shape. I cleaned it the best i could with some brake cleaner, for shigs i through the DMM on it to check the Ohms and it was a nice solid zero. I removed the fuel level sending unit to check and see if there was something obviously wrong with it, and it was clean and in tact. It has the case of only wanting to work when the tank is almost empty, most other times its all the way to the F. I sprayed it don with some brake clean and made sure to move it around while doing it to try and remove any grit that was in between the contacts on the arm. Conveniently enough it started working again, who would have thunk.

3. Here is the crappy part about this experience, when i was pulling the pump out of the tank I heard something moving around in the tank. After testing and cleaning the pump and such, I decided to probe around with my trusty magnet (in hindsight probably not the best idea). Originally I did this to make sure there wasn't any metal pieces in the bottom of the tank. I didnt find any small metal parts, the only thing I came up with was the gigantic baffle that use to be fastened to the tank. So at this point not only am I looking at upgrading the pump, I will now be looking at a new tank. Surprisingly enough the tank was clean and there wasnt any rust in it. By the way I had changed the fuel filter a couple weeks ago.

I reassembled everything and stuffed the pump into the middle of the baffle to hopefully keep it somewhat stationary or at least not floating all over the place in the tank until I can get the replacement.

4. Next we started it up, I had the neutral position switch unplugged for some reason under the car, so we plugged that back in. While it was running and up on jack stands, I started trouble shooting some other stuff. Shook and wiggled the crap out of the Ten Pins and twisted and messed with the wiring of any of the injectors that i could get to and there were no changes.

Unplugged the MAF while it was running and it died like always. Started it back up with it unhooked and it barely ran, had to give it some throttle to get some sort of steadiness to it. Plugged it back in and no change.

Next I was on to the O2 sensors, while it was running I unplugged them and the only change that I noticed was that the idle didnt surge as much as it had been but the car still sounded like it was misfiring or something like it has been. I let the car run for a little bit until finally it tripped the check engine light. We restarted the car with them unplugged and there was no change in anything. I plugged them back in while running and moved on.

I checked around all the vacuum lines and such moving them unplugging and capping them as I went and nothing changed. I took off the vac line from the FPR and capped it with my finger.The idle sped up a few hundred rpms and held steady but still had what sounded like cross or misfiring, im pretty sure on that note that i have the appropriate plug wires routed to avoid that.

So now it was time for the road test, and to my suprise it ran pretty damn good but it was still lacking what it could be.
89 stang when it decides to run right - YouTube

The vid above is a mild 1st to second pull and had to let out of it because the road turns hard right. But as you can tell its roasting the tires down the street. When it runs at its worst it wont do this at all, sometimes wont even so much as bark the tires going to second.

I dont know what we did today but something worked, and we never took off the cable to the battery so the computer had not been reset.

What do you think.

Matt

 

[Muttstang89]

Trey, I have my original mass air meter and housing and have swapped it back and forth with not change, other than the 70mm unit gives it a lilttle more spunk it seems. the housing and meter of the 70mm unit looks like this:

70mm Cobra MAF Housing