trick flow running rich MAF conversion

[scottyko88]

I have posted before about my car. I have an 87 5.0 with a trick flow kit from summit. heads intake cam etc. 24 lb injectors 255lph fuel pump, 91 or so computer and wiring harness. (it has the air bag connectors on it) We have tried everything including changing computer. however I did not change the engine harness so the 91 harness from the computer plugs into the 87 underhood engine harness. I am thinking that its possible that the temp control sensor is is not hooked up or the wires suppose to be going to it are not there. The car runs alot better cold, then turning around and coming back runs very bad. I think that the computer could not be reading that sensor therefor throwing fuel to the car? Does anyone know if that is or could be the problem.? Anyone have any other suggestions to what it could be? Anyone ever done a maf conversion without changing engine harness?

THanks for your help

[349Stroker]

can't use the 91 harness ans I have also heard of fire being cause by doing this

you can only use an 89 mass air harness for 87-89 cars


all you need is the mass air plug with the wires on it(which you can get from ebay) and I believe you get instructions on which pins to put the 4 wires in and that will be all you need

I would suggest getting the 91 harness out or put the complete dash harness in from the 91 and then it should work

[scottyko88]

even with a 91 computer in it? I never heard of that? all the interior stuff works.. everything works inside the only thing thats going on is the motor is not running right when warm

[349Stroker]

all the gauges work?

an A9L is used in 89-92's

any mass air comp will work in any mass air car

[scottyko88]

no that is another thing. the oil pressure gauge doesn't work. The temp gauge will work but not with what is suppose to be hooked up under the hood. what is suppose to be oil pressure sending wire is temp and what is suppose to be temp is not oil nor is it temp. I can't remember what numbers and letters are on my computer. AP9 or APL9 or something like that but im not sure.

[scottyko88]

but yes to answer the question.. it does have a mass air computer and wiring harness in it! but not engine harness which consist of tps/temp control/temp gauge sending wire/and oil pressure sending wire. (not sure what the proper name is for a sending wire)

[ArmyWarrant]

There is pinout issues where the main harness interfaces with the dash harness behind the drivers strut tower between the 87 and 91 harnesses. There is something between the interface that stops the ignition signal fro going through to the EEC I believe. As stated the easiest way without an 89 harness is to use the mass air wires from the 91 harness on your stock harness. I have a link here that break down the swap very good and tells you exactly what pins to place the mass air harness wires in in th eec 60 pin connector.

http://www.popsracing.com/tech/mafconversion.pdf

Very thorough, follow the article to the t and everything will work out perfectly.

[349Stroker]

all those wires are in the injector harness.They are all the same.The gauges don't work because the 2 plugs that connect the engine harness to the dash harness(by the wiper motor) don't match up from plug to plug.You are crossing wires up right there

[scottyko88]

The gauges are not the conern for me. Its the fact that the car isn't running correctly. My main question to everyone is if my temp control sensor on the pass. side of the car is not being read by the computer will it just keep dumping fuel to the car thinking that the motor is cold.

[ArmyWarrant]

In your OP you said tha tyou swapped the harness from the computer to the under hood engine harness. The harness that comes from the EEC interfaces with the dash harness on the drivers side behind the strut tower. The problem is that the two harness are different. Your car will not ever run right unless you fix the pin out issues. It is a long tidius process and really is hard to do unless you have someone who has access to the factory wiring schematics. I did this swap in my 88 GT vert and had the exact same problems. The Computer harness is your problem. There are big differences in the pinouts of the 1991 and 1987 wiring harnesses that is why you have sensors swapped on the gauge reading and such. I would seriously recommend stripping the MAF wires out of that 91 harness and installing them in your 87 stock harness if you still have it.

[ArmyWarrant]

???? does the car run at all right now?

[349Stroker]

if you mean the ECT in the heater crossover?

yes it will dump fuel.all the fuel your car has.check the voltage there.It should read close to the IAT sensor


The gauges are not the conern for me. Its the fact that the car isn't running correctly. My main question to everyone is if my temp control sensor on the pass. side of the car is not being read by the computer will it just keep dumping fuel to the car thinking that the motor is cold.

[scottyko88]

ok thanks. I was told to use a mass air computer and a mass air wiring harness and that would be better than hacking into the main harness. thats why I got that harness. I guess thats my next step

[scottyko88]

sorry reading a bunch of threads.... yes the car runs.. it idles well, revs great, but running it down the rd the car misses really bad at like 3000 rpm until about 4500 or 5000 then runs outta it.

for the other thread yea the ect is what I was talking about. I was aimming at that being my problem, I was going to check the harness for those wires to be sure they are running to the right pin. btw my friends 93 5.0 runs with the tps unhooked by mine does not. it stalls out right away. that was another test we have ran

[scottyko88]

So what your telling me mass air conversion can only be out of a 89 mustang 5.0? or the kit you can buy or by making it maf out of my 87 harness

[ArmyWarrant]

So what your telling me mass air conversion can only be out of a 89 mustang 5.0? or the kit you can buy or by making it maf out of my 87 harness

It can be done with the 91 harness but it isn't easy at all. if you compare the connectors behind the drivers strut tower you will notice that there are differences in the wiring pinouts. I hate to say it but unless you have a factory schematic for both years it is going to be hard to get it right. If you had those you could compare each connector and repin them to match each other.

[ArmyWarrant]

ok thanks. I was told to use a mass air computer and a mass air wiring harness and that would be better than hacking into the main harness. thats why I got that harness. I guess thats my next step

Well this is more than what my car did using a airbag car harness. I boughtmine being led to believe it was an 89 and when I got it it had the air bag sensor connectors. I ended up stripping the maf wires out of the airbag car harness and putting them in my stock harness. As soon as I did that and followed the remainder of the steps in the tech article I linked to before it ran like a champ.

[scottyko88]

thanks for your help but we found that 2 wires controlling the mass air were cut and not connected to the computer. we re-pined them to the proper place and she runs great. No more miss. a little timing adjustment some 3:73 and it will be great. thanks for your help

[ArmyWarrant]

:thmbsup: