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1986 Ford Mustang GT Smelling - Fuel System
Question: I have recently completed a full custom job on an 86' GT with the "Roller" motor and 351 firing order.
It has a comp polymer power box intake as well as MSD 6al ignition, MSD Blaster, and MSD Billet Distributer. I am using Taylor perf wires, a 70mm
throttle body, March Cold air system, K&N High Flow Air Cleaner, 36lb injectors, as well as an adjustable fuel regulator. True Off Road X-pipe 3" connected to Hedman long tube headers ( what a pain in the ass they were ) I wanted to tell what I had to give you some ideas of where I might start as far as mixture. It runs rich, yes the o2 sensors are still installed. SO rich that at times it can burn the eyes if standing close for a long time.
It has a holley high volume fuel pump and millen high volume oil sending unit as well as a Moroso 7qt pan with windage tray. In all my excitement of getting through with this money pit, what did I overlook? TPS is good, EGR valve seems okay. I had the temp sens checked with a FLUKE II was told it was cool beans.Where.....what..... Even if it is a bit rich it seems to idle at about 950, and it has no hesitations... just stinks....
Thanks for any info....
Sean - 86' GT 2nd Owner... bought in 94' for $1800.00... was black... is now Competition Yellow ( Dupont base coat clear coat ) with Saleen wing and Ram Air hood...
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Technican: Sean,
I do not have the exact specs here, but if you put larger injectors in, it will make the car run richer. The larger the injector, the richer it will run. THE INJECTOR MUST BE MATCHED TO YOUR ENGINE, OR YOU ARE GOING TO DROWN. The computer (with the oxygen sensors) can control the fuel a limited amount, ususally 25% more or less. Anything outside that range will not be adjusted to. Even within that range, the engine will need to run for a while, and the fuel system go into closed loop for the computer to adjust. For testing purposes, you can reduce your fuel pressure which will have some effect on the richness, but you will also lose some burn quality if you get below 30psi. Check with the injector people about proper injector size. You can also watch the oxygen sensors with a digital voltmeter to confirm what is happening. 0.7-1.0 volts is rich. 0.0-0.3 volts is lean. If all is working well, the voltage should cycle from rich to lean 6-15 times in 10 seconds at idle, faster at higher RPMs.
Owner: I understand about the injector size and its ratio to air and richness, or drowning. I checked around before committing to replacing the injectors. It was easy as could be since that big aluminum plenum was junked years ago, and the power box makes it a 1 2 3 step deal to remove the entire harness and then the rail.
I have lowered ( and raised ) the psi. A stock motor is set to run from 27-32 being in safe range.
With the heads I put on I was cautious in the injector selection. A friend went with 40lb, and talk about drowning.... KASPLASH!!
I checked the o2's to your specs... all is cool there. What about the smog/ emissions bullshit to the passenger side front. Vaccum lines etc etc.
Since it is not Mass Air, what dictates the mixture.
I have the psi @ 30-31 and with GT 40 heads, I didn't want to starve the motor. It was idling at around 950 and I located a small leak in Power Box next to a fitting. Fixed it, adjust the idle, and now it sits around 700 with a nice growl, light lope, makes one guess what is under the hood, but still rich. Should I put back the origial size injectors, but new? Or compensate as I did with the regulator? I can raise it as high as 50, which is nuts or drop it below 20. I have an inline fuel pressure gauge, and a pro comp fuel guage pod mounted on the pillar. I still sense a vac leak that the noise of the motor is concealing but tried the spraying of ether to see if it picked it up without success.
On a motor with high miles, rebuilt bottom end and new top end, does the altering of OEM parts have any impact in this area.MSD, Mallory etc etc.
On my 90' notchback 1/4 mile toy. I can hook my 2.6 ghz Pavilion with a software package from a company out of Cali called STI CompWare. It is made for the interrupter you install in between the ECM and the end of the harness. It has a serial adapter that connects to it and then a USB 2.0 cable for the PC.
Real time telemetry, and for someone like myself, a cool shortcut for insight to what is taking place under the hood. If you know of something similar for the older stangs... 87 and down, please share.
I appreciate your input on this.
The one I am talking about the 86' the rich running one, can I use the 90' as a template for troubleshooting?other than the Mass Air and a few fuel delivery alterations, the vac lines seem close and the harnesses damn near identical. The ECM's aren't. I have the 90' running 10's and even broke into the 9's twice. I got the car for free for doing a tranny in a wrecker, and then the harness in the slide which kept getting pinched when loading a car. Easy... and the car was payment.
The 90' that is. I have around $9300.00 in parts from the ponies with MT Street Et's, ( it is not street legal ) to the .455 Richmond Geared Ford 9 inch rear end. King Cobra clutch, and the list goes on. It runs as clean as a hair dryer, with barely a hint of carbon at all. I run amsoil in it as well as VP racing fuel. different application but almost the same setup in the 86'. I did install a pulley kit as well as braided lines and high temp hoses.
Is there a checkist you can pass on to me as to what to check and in what order. I have a Fluke II and a Fluke 90IV for testing resistance and volts.
Other than a service manual is there a site or a place to order diagrams for vac and wiring. The 86' schematics are a bit rough. The 90' they got much more simple with wiring, just more complex with mass and the mapping. Am I far off, or am I on the right track. I'm confident in the aftermarket parts I buy, just not confident in the variations even if by a little 86' - 90' exhibit. My 66' is a walk in the park with a GPS and a you are here map. So simple... old school. even installed the after market under dash A/C from scratch and converted it to 134a, and the alt to a 130amp. I'm doing a motor for it now, pulled the worn and torn 200 straight 6 for rebuild to sell with it when the time comes, and installing a s281, waiting on retro kit and bell housing.
I like your site and your answers seem evel keel. even if the person, or IEN is asking how to set a stereo, or how to put a 427 cobra jet into a Ford Festiva.
Technican: I do not know sites for the information you request. The ideal for your car would be a programable computer, that way you can shorten the injector time when unloaded, and let them flow when the need is present. ...however... if the o2s are showing rich, the fuel MUST be decreased. If they are cycling, then the mix is right and the rich smell may be coming from an unbalance from cylinder to cylinder (faulty injector or vacuum leak) If you want to change the injectors, the choice is yours whether old injectors, or smaller new units. 10% difference in fuel volume WILL make a difference in the way it runs! Unadjusted, 20% out WILL make it run poorly. Here's How To Get Guaranteed Solutions In Minutes
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