Strange Idle problem

[Red91SiT]

I have just converted my car to Mass Air Flow, the problem is when i start it up on these freezing days, it quickly revs up as it's supposed to, and then it promptly dies. The only way to keep it running is to rev the engine up a bit. Once it's warmed up a bit it will sit there idleing super low (the lights actually dim). It also misfires a lot at idle, if i rev it up it does fine. but at idle, weather its' in gear or not it will die. This is really not nice since the roads around here are icey, i have to sit there one foot on gas, one on brake spinning hte tires on the ice until i can go.

[nailfoot]

Isn't there an idle adjustment screw on the 5.0? Seems I remember adjusting one on my 1989.

[Mr Wiggl3s]

Ya there is

all i know is that its on the left side by the manifold (right)

ill look in my hayness if no one else answers this for you

It seems like its not getting the correct amount of fuel though

[OVERKILL]

You are not supposed to touch the idle set screw, its set from the factory.

Of course, I've turned mine, but that's because I'm in the same boat with my HO conversion, which wouldn't idle. I've got other issues (its still rich damn it!)

but I would try first pulling codes.


How does it run under acceleration, does it lug and lurch? When I did the MAF conversion on my '87 GT, it did a similar thing and it ended up being the ground wire (black) to the MAF from the ECM had a break in it.

[Red91SiT]

It runs absolutely great all through the power band, except at 0% throttle pressure. (seems to be a good bit more powerful, and mileage is above 20mph even with nearly all city driving. and a few beautiful powerslides.

The idle adjustment screw is not the problem. It definetly seems to be a fueling problem. I have just resetted the idle again and will have an update on the situation tonite.

Do you think it could be from the maf being at the very end of the air intake? I could see some turbulence being created by the different air flows around the fliter as well as air being blown by the radiator fan.

[OVERKILL]

You don't have the filter shielded from the fan? Fan wash is a big issue on the MAF's on Fox-body Mustangs for people that do an underhood CAI (which is anything BUT cold air) and the typical solution is to install a shield to prevent it. Is the car running rich?

[gadget73]

Is the TPS correctly calibrated? Should be somewhere in the 0.95-1.0 volt range with the throttle closed. Bad TPS can also sometimes cause this.

What motor and ECM mix are you running, stock lopo with 91 Cali Vic mass air or are you running an HO or something?

[Red91SiT]

You don't have the filter shielded from the fan? Fan wash is a big issue on the MAF's on Fox-body Mustangs for people that do an underhood CAI (which is anything BUT cold air) and the typical solution is to install a shield to prevent it. Is the car running rich?


haha, it's pretty much right behind hte fan, so that would explain nearly everthing, it starts fine, then the fan spools up and she dies.

I'll have to attempt a little fixt it tonight thank you.

I'm running an A9L, the maf i'm unsure of, all i know is it's 19 lb/h calibrated (my car came with 19 lb/h injectors) I'll have to check the tps as well

[gadget73]

What cam are you running, HO cam?

[Red91SiT]

lol, what you think i'm rich or somethign?

nah, hte only reason i'm running a maf/ho comptuer conversion is because my car had 7 19lb/h injectors in it. I checked prices and decided it would be cheaper (and easier) to just convert it to maf and get one more 19 lb/h injector. So that's what i did! I"ve put a carboard tube around the filter so if the fan is causing the problems it should smooth out the air flow and make it run ok. An added side benefit, it keeps power steering fluid from spraying into the air filter wahoo!!

[OVERKILL]

So you are running the stock TC camshaft?

Uh oh :(

It has the old 302 firing order, the A9L has the HO/351 firing order, 1-3-7-2-6-5-4-8 and so you've got an interesting setup right now.........

[Red91SiT]

yes, the fuel injectors aren't going to their respective cylinders, but this seams like it should mostly only affect the vehicle once it is warmed up and using the 02 sensors. There it has no problems :D (also can't do cylinder balance tests very easily)

BTW- after watching some old hyundai and saab promotional videos, i have a strong urge to drive balancing on only two wheels, so if i quit posting on here, its probobly because they stole the comptuer for driving dumb.

[gadget73]

You could re-pin the injector harness to make it match up. I'm kind of surprised you don't have issues with the fuel mix running horribly fat with those 19 lb injectors.

I might actually go mass air on my car once I swap the heads, depending how it runs. The new heads and intake setup should move a fair bit more air than stock, even with the stock camshaft. Mostly this would be an effort to get more fuel economy out of it, power increase would be secondary. I figure more accurate metering should produce a better fuel mix, therefore more power and economy. We'll see how the SD works out first before I get silly though.

[OVERKILL]

You could re-pin the injector harness to make it match up. I'm kind of surprised you don't have issues with the fuel mix running horribly fat with those 19 lb injectors.

I might actually go mass air on my car once I swap the heads, depending how it runs. The new heads and intake setup should move a fair bit more air than stock, even with the stock camshaft. Mostly this would be an effort to get more fuel economy out of it, power increase would be secondary. I figure more accurate metering should produce a better fuel mix, therefore more power and economy. We'll see how the SD works out first before I get silly though.

The SD Mustangs are actually faster than the MAF cars stock :)

If you are using a Mark VII ECM (19lb) you'll be fine gadget, at least that's what the guide says and my car seems to work OK (besides my fun tuning issues) with it.

It isn't air flow that causes issues with the SD ECM, its the loss of vacuum caused by running different cams that really throw a wrench in things.

[Red91SiT]

You could re-pin the injector harness to make it match up. I'm kind of surprised you don't have issues with the fuel mix running horribly fat with those 19 lb injectors.

I might actually go mass air on my car once I swap the heads, depending how it runs. The new heads and intake setup should move a fair bit more air than stock, even with the stock camshaft. Mostly this would be an effort to get more fuel economy out of it, power increase would be secondary. I figure more accurate metering should produce a better fuel mix, therefore more power and economy. We'll see how the SD works out first before I get silly though.

I have a High Output comptuer, so its' setup for 19 lb/h injectors :-)

BTW i've put a air smoother outter on the filter, and it still dies. It seems directly related to temperature though, the colder it is, the worse it dies :S. I have a new Air Charge Temp sensor, so it shouldn't be that. I"m still conused, I'm igoing to go check the tps voltage. I'll have an update shortly

[Red91SiT]

AHH!! the code output connectors are screwed up some how! I go and connect it as shown, and the cel stays on, i turn the ignition off, and the light stays on, i turn the key to ignition, and it stays on! boooo What could be causing this?!

It seems to be connected correctly. When i turn the key everything makes the whirring noises and the relays do thier clicking, The light seems connected correctly because when it's on haha, i'm confused :-(

[OVERKILL]

You wire that MAF stuff in yourself? What guide did you use?

[Red91SiT]

You wire that MAF stuff in yourself? What guide did you use?

Yes i did :-) I used a combination of Pin out diagrams for 86-89 Grand Marquis/Crown Vic's and A9L pin out diagrams, and the maf conversion guide posted in the tech section.

I think it's wired correctly, maybe it's a bad ecu output?

Also the Idle Control Valve seems like it's either wide open (overly fast idle) or slammed shut (misfiring like a monkey) and then refuses to open again when i shift gears, so it dies :-(

(edit) also remembered that my VSS sensor signal is not connected, but this doen'st seem like it should be afffecting this? And the A9l is a manual ecc, but they say it usually works fine in auto's. (slightly less rpm on engine braking)

[OVERKILL]

There is a guide for MAF conversion on Stangnet that I used to do my conversion on my '87 GT. The car ran like a top. Might want to check it out and just compare it to what you've done.

[Red91SiT]

Sounds like it's VSS related according to the stangnet article, I'll have to do that asap. (so damn cold though)

[gadget73]

I have a High Output comptuer, so its' setup for 19 lb/h injectors :-)



Yes, but its also assuming 19 lb injectors and an HO camshaft and E7 heads, which move an awful lot more air than the lopo motor does. It might still be able to sort of figure itself out but it wont quite be ideal.

[Red91SiT]

Yes, but its also assuming 19 lb injectors and an HO camshaft and E7 heads, which move an awful lot more air than the lopo motor does. It might still be able to sort of figure itself out but it wont quite be ideal.

Hmm very good point. I"m starting to think it's perhaps ECT related, when the motor's warm it starts right up, and the idle is improving (eec adjusting?)

[gadget73]

Could be, meter out the sensor and see what it says.

http://fordfuelinjection.com/index.php?p=28

[Red91SiT]

Well, I've cleaned the MAF, and found that is is still running LEAN at idle. It will crank a bit backfiring once in a while until it finally gets going, then I have to rev it up a goood bit or it will die. I have to hold it at overly high rpms, while it's -10 F for a while before it will idle by itself. I really feel bad for the motor everytime i do this :-( Also, unplugging the ECT sensor doens't change anything. Surpsingly same with the MAF sensor. Unplugging the TPS just opens the IACV a bit. Of course unplugging anyof these screws it up when it's warmed up. So I'm a bit more confused. I'm thinking maybe just jump for the FordEMU and add some start up fuel?

[gadget73]

Considering you're running an ECM designed for an HO using 19 lb injectors on a lopo motor, I'm not too surprised the fuel mix is off at low speed. I really don't think you're going to be able to expect the ECM to run 100% correctly on an engine thats not what it was designed to operate.

[OVERKILL]

Considering you're running an ECM designed for an HO using 19 lb injectors on a lopo motor, I'm not too surprised the fuel mix is off at low speed. I really don't think you're going to be able to expect the ECM to run 100% correctly on an engine thats not what it was designed to operate.

Bingo.

[Red91SiT]

Well, I feel a good bit stoopider today, but i realized i forgot to bolt my distributor down "DOH" so I adjusted it back to where it's supposed to be and so far it's working "knocks on wood with 4 leaf clovers painted on it tied to rabbit feet, while crossing my legs"

[87 town]

I have just converted my car to Mass Air Flow, the problem is when i start it up on these freezing days, it quickly revs up as it's supposed to, and then it promptly dies. The only way to keep it running is to rev the engine up a bit. Once it's warmed up a bit it will sit there idleing super low (the lights actually dim). It also misfires a lot at idle, if i rev it up it does fine. but at idle, weather its' in gear or not it will die. This is really not nice since the roads around here are icey, i have to sit there one foot on gas, one on brake spinning hte tires on the ice until i can go.
Not supposed to mess with idle setting. (I have tried and it doesn't seem to stick anyhow). I would look into IAC (Idle Air Control Motor) which controls idle. If not ideling correctly, this is first place I would look. Problem would be most prevelant during cold start up time. Cost maybe $75 to $100 and an easy install. Naturally, test the one you have first...or maybe...it may not be plugged in correctly or loose?

[OVERKILL]

Not supposed to mess with idle setting. (I have tried and it doesn't seem to stick anyhow). I would look into IAC (Idle Air Control Motor) which controls idle. If not ideling correctly, this is first place I would look. Problem would be most prevelant during cold start up time. Cost maybe $75 to $100 and an easy install. Naturally, test the one you have first...or maybe...it may not be plugged in correctly or loose?

AC Delco combustion chamber cleaner works wonders on dirty IAC's.