Engine problem driving me crazy, nothing I try seems to be working, please advise!!!

hydra · Jun 9, 2006

Hello everybody,
First some background info:
I have a gulf-spec (no cats or O2 sensors) 1989 Mustang GT with a 1998 Ford Explorer 5.0 engine, the one with the GT-40P setup. Car was dead/stationary for 2 years or so because the old HO engine blew a head gasket. I decided I needed a cheap/cheerful daily driver so I finally gave in and put the hot '98 engine in last week. Problem is the car runs horribly, belching out obscene amounts of black smoke and consuming ridiculous amounts of gas. My first thoughts were that the MAF was shot, especially because the car wouldn't change when I unplugged it. Put it on the scanner and it threw out an absurd number of codes, some of which have no relevance whatsoever. No MAF codes though, even when I unplugged it... I tried several other MAFs with little to no avail. Driver side cylinders didn't seem to be firing (engine wouldn't change when I took the plug leads out). Plugs were all quite sooty so I changed them out for new ones. I discovered that 2 of the driver-side injectors were spraying poorly and the other two weren't spraying much at all so I bypassed the fuel pump and ran some injector cleaner through the injectors. Fuel pressure is a little low at 30psi even though the fuel pump was replaced not too long before the car was parked... Despite all this the car is still running AWEFULLY with no power. I'm at my wits end here, my only hope is that the computer might be somehow shot (we opened it up and it looks like it did the day it left its maker) and that replacing it will make the problems magically go away... What I don't get though is why would the computer go crazy if it was running fine before and the car was stationary since? I've got a spare A9P computer, but its a long drive away from here and I don't want to go all the way there for nothing... What do you guys think? Please advise...

KENS89LX · Jun 9, 2006

Check and see if the 98 engine injectors are a different lbs than a 89. What all did you swap from the 89 to the 98 engine? intake, wiring? Also check out the MAP sensor that will screw with the computer..sending more fuel than needed!

86bluecobra · Jun 9, 2006

well you did say no o2 sensors right. the o2 sensor has a little info for the computer as to how lean or rich the car is. I would think that the computer would need them. mind you that is more of an idle issue with o2 sensor's i believe. Any chance you have a bad vacuum leak? have you checked the timing?

hydra · Jun 10, 2006

Gentlemen,

The explorer injectors are the same 19lb/hr pieces as the mustang injectors so there should be no problem there. Besides, I had the engine in the car for a while a long time ago and it ran fine.
The only '98 parts on the car are dumb metal pieces with no electronics (except for the injectors), the rest of the car being stock '89 GT...
Car is MAF and not MAP. We checked the BP sensor and it seems to be working fine.

As for the 02 sensors, the car never came with any (no cats either) from the factory, as this is a gulf/middle-eastern spec car. I've had this car for little over 4 years now and it used to run fine and return good mileage, once upon a time. I don't have any vacuum leaks, and timing is fine. Besides, don't vacuum leaks make an engine run lean? I swear the car is going through a quart of gas in a few minutes!

86bluecobra · Jun 10, 2006

yes the vacuum leak would make it run lean. is there any chance that some injectors are staying open? i mean you say the pressure is 30psi. is that because of constang flow through an injector or 2? i know its more of a carb problem like dirt in a needle but if you are that rich with low psi logic would tell me that fuel must be flowing into the egine when it isn't supposed to be.

MustangGT92 · Jun 10, 2006

do you have an ajustable fuel pressure regulator????

vristang · Jun 10, 2006

I want to hear more about this gulf spec car. What catch code is the computer? Still A9L? Do you have plugs for the O2s? Not using O2s seems scary to me, and I have never heard of this setup from Ford. I'm not saying it didn't come that way, just asking for more info.

I assume the wiring harnes from the Mustang was used?

Bad fuel (after sitting for several years) can cause some serious issues.
Have you replaced the fuel filter?

Are you checking the fuel pressure with the vac line disconnected?

These may seem like dorky questions, but we have to double check eachother.

Did you have to relocate ANY sensors?

jason

hydra · Jun 12, 2006

I performed a bunch of checks on the ECU connector and individual sensors and they all came out fine with one small anomaly, the voltage to the MAF at KOEO is ~8.5V which seemed abnormally high to me. So basically it seems like the computer is fried. Why? I have no idea. In any case I got the spare A9P computer I have, plugged it in, only to find that my fuel pump isn't working all of a sudden. After that I just ran out of time for the day... Any suggestions as to why that is? What should I do next?

Oh and Jason, all the stock Mustang wiring was used. The Explorer engine is just a "dumb" chunk of metal (with the exception of the injectors, but they interchange anyway)

All the old fuel was removed/used up a while back

I'm checking fuel pressure with the line connected

No sensors were harmed or relocated in this conversion

v8only · Jun 12, 2006

hey, I've had the EXACT same problem, right to the tee.

97 explorer engine in an 86 gt vert running speed density. HO roller cam in the explorer block along with tfs valve springs. Nothing the mustang speed density computer would disagree with.

I've had some REALLY knoweledgeable friends look at this, and I'm still nowhere.

I've torn it down to almost a shortblock, and built it back up at least 5 times now. I've swapped out the explorer injectors for HO mustang injectors and fuel rail that were known good ones. I've swapped the map sensor, I've checked for vaccuum leaks, i've drilled the lower properly for act and egr return.

It belches out clouds and clouds of black smoke, and fouls the plugs in minutes.

the ONLY thing I've been able to find is that I'm running 12-13 pounds of vaccuum, which is WAY too low for speed density. I believe the ecu is therefore dumping too much gas in thinking I have a full throttle condition.

I have checked for vaccuum leaks, so my problem may be indicative of something else that's gone wrong, and...after reading your thread we may be in the same boat. ****, I have been through everything, I've messed with the egr, you name it.

we should chat more, even over the phone. I'm currently in process of giving up on the explorer deal, and I'm going to swap on stock e7's and a stock intake, just in case I have a mechanical issue some where. I don't know, I'm stumped, and this has been going on for more than a year. I've torn it down and built it back up so many times, that I couldn't possibly be more burnt out on this project. Please keep me updated, or send me a pm.

vristang · Jun 12, 2006

hydra said:
I performed a bunch of checks on the ECU connector and individual sensors and they all came out fine with one small anomaly, the voltage to the MAF at KOEO is ~8.5V which seemed abnormally high to me. So basically it seems like the computer is fried. Why? I have no idea. In any case I got the spare A9P computer I have, plugged it in, only to find that my fuel pump isn't working all of a sudden. After that I just ran out of time for the day... Any suggestions as to why that is? What should I do next?

Oh and Jason, all the stock Mustang wiring was used. The Explorer engine is just a "dumb" chunk of metal (with the exception of the injectors, but they interchange anyway)

All the old fuel was removed/used up a while back

I'm checking fuel pressure with the line connected

No sensors were harmed or relocated in this conversion

The MAF supply voltage is a major problem. The MAF runs off the vRef voltage just like the ECT, ACT, TPS, etc. This is supposed to be a 0-5v scale. I suggest starting a new thread about how to check for correct vRef voltage from the ecu. Once you get a response from a guy named JRichker, you will be set. I have no idea how to check that though.

Some of the A9* computers were wired a little different for the fuel pump. Your pump is probably ok, but to use the A9P computer you will have to do some re-wiring (assuming I am correct). My memory is a little hazy on the details here, but you may find some info if you do a search for MAF/SD conversions and computer selection.

Fuel pressure should be checked with the vac line pulled from the regulator and plugged (so that it is not a vac leak). You should be set to about 38-39psi with the vac line off. This may be a contributing factor.

I am still curious about this non-O2 configuration. I really want to know what would happen if you plugged in some O2s. Does the car have plugs for O2s?
I guess my question is if the computer was tuned differently or if the factory just let it run in Open Loop.

jason

Blue89gt · Jun 12, 2006

you could check and make sure you have a GOOD solid ground to the transmission/ engine to battery... good luck.

jrichker · Jun 12, 2006

Post the codes. There could be some major help towards getting your problems fixed.

hydra · Jun 13, 2006

Thank you for all your feedback guys.
First off BOTH computers are A9Ps. My car never came with HEGOs or cats. In fact I remember my old (stock) headers didn't even have provisions for O2 sensors until I replaced them with a cleaner set of headers off a '94. My wiring harness doesn't even have the "extension" for the HEGOS that mounts aft of the fuel pump relay underneath the MAF. Oddly enough my '89 vert parts car (which I nabbed the spare ECU off of), which has a similar set-up has this HEGO harness extension, but no provision for the O2 sensors in the headers either - go figure! Once again, I've owned my car for several years now, and it used to run fine and return decent gas mileage..

Back to what's important though..
My fuel pump issue is unrelated to the change in ECUs, because when I returned the old ECU the problem persisted. I'll need to take a closer look at it tomorrow morning (in 10 hours)

All grounds are fine, I checked them with a voltmeter at the ECU connector and everything seemed fine, except for the MAF SIG to ground, which was much higher than it should have been...

JRichter,
The codes the car threw out were just nonsense. I don't recall the exact numbers, but they were things like auto tranny temp overheat, faulty lock-up solenoid, power steering pressure sensor, coolant fan, and some other crap like that. I clear the codes and they'd come back at me as soon as I do the KOEO test... I'd unplug the MAF to get it to give me a MAF code and it wouldn't do that either. Weird stuff I tell you, any suggestions?

Modular2v · Jun 13, 2006

one is a 19lb and the other is a 24lb......the 98 is the 24

hydra · Jun 13, 2006

One other thing
I had this very same engine in the car like 2-3 years ago and it ran great at the time, so we're not exactly dealing with an unknown quantity here...

hydra · Jun 13, 2006

Modular2v said:
one is a 19lb and the other is a 24lb......the 98 is the 24

Not true sorry, I made sure of that before using them instead of the stock injectors way back when. Think about it, why would Ford uprate the injectors on a car that's only putting out 215bhp stock?

vristang · Jun 13, 2006

hydra said:
Not true sorry, I made sure of that before using them instead of the stock injectors way back when. Think about it, why would Ford uprate the injectors on a car that's only putting out 215bhp stock?

Be careful, you can't always apply logic to Ford decisions

vristang · Jun 13, 2006

hydra said:
In fact I remember my old (stock) headers didn't even have provisions for O2 sensors until I replaced them with a cleaner set of headers off a '94. My wiring harness doesn't even have the "extension" for the HEGOS that mounts aft of the fuel pump relay underneath the MAF. Oddly enough my '89 vert parts car (which I nabbed the spare ECU off of), which has a similar set-up has this HEGO harness extension, but no provision for the O2 sensors in the headers either - go figure! Once again, I've owned my car for several years now, and it used to run fine and return decent gas mileage..
?

Run the codes again and provide them to JR, he may be able to make sense of them. He's a smart dude.

So far as I know the O2 sensors where never located in the headers/exhaust manifold. They are located in the midpipe, just after the header flange. They should be less than ~18" from the heads.
Maybe someone else can confirm that?

I know it is not what you want to hear, but I can't help but think that part of the problem is that the O2s are not hooked up. Please hear me out.
The cars previous owner could have installed the non emissions midpipe and pulled the plugs for the O2s. Then when he sold the car, made up some bogus "non-emissions equipped vehicle" story. That is what this feels like to me.

You can run any of our cars without the O2 sensors. This forces the computer into running Open Loop, similar to wot. The a/f ratio would be that of wot, which happens to be a little rich.
Perhaps you ran just fine (as many people will when forcing OL this way) for several years, but now have one sensor going bad? Say a ECT or ACT is indicating sub freezing temps?
If this is the case then not only are you running rich because you are forcing OL, but now the computer could be seeing coolant temps of below zero, which would cause more fuel to be added.

This is just my theory.
It does not explain why you had all of the random trouble codes.

If you have any links or other resources for me to read on the gulf-spec setup you have I would greatly appreciate the read.
I'm off to Google it right now.

Good Luck

jason

hydra · Jun 13, 2006

Vristang,
Can you confirm to me (i.e. show me documented proof) that explorer injectors are 24lb/hr and not 19hr/lb? I don't mean to challenge you or come across like a smart-alec, just want to be sure myself.

In any case,
I should add that I currently live out in the middle east. Both of my mustangs have the exact same setup, and my speedo comes in km and not miles. I know that pretty much all the cars that came out here up till around the early-mid 90s were sans catalytic converters and thus (probably) O2 sensors. The previous owner was a girl who couldn't tell you what a HEGO was if her life depended on it. But on the other hand why would these cars get a standard-issue A9P ECM as opposed to something different? The car used to get around 17mpg in stop and go traffic and over 22mpg on the highway. I wish I had more info about this, but I'm afraid I don't. Let me assure you that I'm not making any of this up and that this applies to all cars and not just Mustangs.

A brief rundown of what "gulf-spec" entails or used to:
- no cats in the exhaust and possibly open-loop operation
- heavy-duty cooling system
- uprated AC system
- and possibly a different rear-end ratio but this is anecdotal.

I saw a Porsche Boxster boasting some of these features right on the showroom floor as recently as 96-97

vristang · Jun 13, 2006

hydra said:
Vristang,
Can you confirm to me (i.e. show me documented proof) that explorer injectors are 24lb/hr and not 19hr/lb? I don't mean to challenge you or come across like a smart-alec, just want to be sure myself.

In any case,
I should add that I currently live out in the middle east. Both of my mustangs have the exact same setup, and my speedo comes in km and not miles. I know that pretty much all the cars that came out here up till around the early-mid 90s were sans catalytic converters and thus (probably) O2 sensors. The previous owner was a girl who couldn't tell you what a HEGO was if her life depended on it. But on the other hand why would these cars get a standard-issue A9P ECM as opposed to something different? The car used to get around 17mpg in stop and go traffic and over 22mpg on the highway. I wish I had more info about this, but I'm afraid I don't. Let me assure you that I'm not making any of this up and that this applies to all cars and not just Mustangs.

A brief rundown of what "gulf-spec" entails or used to:
- no cats in the exhaust and possibly open-loop operation
- heavy-duty cooling system
- uprated AC system
- and possibly a different rear-end ratio but this is anecdotal.

I saw a Porsche Boxster boasting some of these features right on the showroom floor as recently as 96-97

First off, I appreciate your patience with me trying to learn about your setup. I know it can be frustrating to have someone questioning you especially the way I have been. Hope it doesn't come out rude.
From what I found with Google...
Many cars are setup this way, no cats and no O2s. The reason seemed to be leaded fuel that is still used overseas, which would render these 2 things useless in short order. Is leaded fuel availalble in your area? Where did the Explorer motor come from? Are the valves in the Explorer motor appropriate for leaded fuel?

The reason I am so fixated on the O2s is that they are the only feedback to the computer on what the a/f ratio is. With out O2s the computer has no idea what is actually happening in the motor. The computer will just follow the pre-programmed tables, and think all is well. Even if the ECT/ACT are providing crazy signals.

If Ford knew there was not going to be any input from the O2 sensors on these cars, they may have changed some of the program. It is concievable that your open loop settings are a comprimise between OL and CL from a US puter. This is just speculation on my part though, but I am curious about the tune.

On a side note, having or not having cats does not influence whether or not you need O2s. The primary function of the O2 is to provide feedback to the computer on a/f ratio. If 2 sets of O2s are used (similar to OBD2 cars) you can use the O2s to check the effectiveness of the cats. Single O2s (like the A9* puters) are mounted before the cat and are not used for the cats in any way.
Probably trivial at this point.

Let me know what you think about the leaded fuel question I posed.

This is a pretty interesting thread

jason

Engine problem driving me crazy, nothing I try seems to be working, please advise!!!

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