Ford OBD1 computer. Wish I had a carburetor

Dirtracer 619

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I have so much time and money not this computer. So frustrated with it, Can't seem to get it to run smooth. Loads up pops in intake. Basically runs like poop then runs like crazy good. So undependable. I guess I'm just not smart enough. Been to Dyno twice. Ran great then for no reason runs flat. So any expert tuners out there im in Ramona but can trailer it anywhere

Specs are it is. Obd1 chipped and tuned
Grounds are all triple checked
Maf is tuned to the 36# injectors

I just don't know what to do to make it dependable

Back at it Thursday. PS. How can you tell if computer is bad does I just stop working
 

S00TLYFE

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Have you talked to Steve at Powertrain Dynamics in Huntington Beach? Dude did wonders for my buddies 408 Windsor Bronco.
 

Dirtracer 619

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I will call tomorrow
 

Dirtracer 619

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Thinking about getting a replacement computer called a Megasquirt (no jokes please). Anyone have any experience with these computers or obd1's in general
 

S00TLYFE

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I haven’t heard of anyone running it on a desert truck, know some guys that have run it on street and drift cars but honestly at that point I’d go with something simpler like FItech or Holley Sniper
 

Dirtracer 619

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Yea. If i make a move. Its gonna be a holly sniper system or the terminator ststem
 

Bert is my name

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I'd check out the fox body mustang forums and see what they are doing for a similar combination. Might find an answer there.
Have you tried unplugging all of your sensor and p.c.m. connectors and cleaning them?
 

Bert is my name

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Popping in the intake is usually incorrect ignition timing. Could also be an intake valve not seating correctly. I've also seen weak or broken valve springs cause backfiring. If it runs good at high r.p.m. and poor down low I would be suspicious of the valve springs/valve train. If it ran well before the engine build but not after. I would verify that the engine was put together correctly before blaming the computer.
 

Bert is my name

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Compression tests and leakdown tests will be a quick way to determine if you need to dig back into the engine. Vacuum readings will be helpful with valve train diagnostics.
 

cjohnson

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How can you tell if computer is bad does I just stop working
Unfortunately no. The "computer" is actually made up of many circuits internally. It is fairly common for one of these circuits to degrade and cause problems but the rest of the computer to work normally. The computers have failure codes but they rarely rat themselves out. They usually blame something else.

I had a Dodge Durango that ran great 99% of the time. Occasionally in drive through lanes it would start idling terrible almost to the point of stalling. It took several months to determine the oxygen sensor input to the computer had a lower than normal resistance due to a partially blown transistor. The drive through thing must have been Murphy's law because it would not do it at home no matter how long I left it idling.

The best way to narrow it down is to get another computer and see if the issue goes away.
 

Bert is my name

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I've seen solder joints break and cause intermittent contact. As well as connectors that will break contact with heating or cooling cycles. The symptoms you describe still sound like valve train or timing issues but without actually seeing and hearing the engine act up it's only a guess. I had a chevy Malibu that I swore had a transmission problem. Turned out to be broken wires in the harness. Intermittent problems are tough to duplicate. A dyno may not duplicate the problem because they usually are tuning for wide open throttle. Being that its obd 1 try a different computer with your prom installed.
 

Bert is my name

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Usually the factory has a diagnostic flow chart that leads you to a bad computer. But that is typically when trying to diagnose a particular set of codes. Or a service bulletin that has the diagnostic procedures to diagnose a bad computer.
 

Josh 8

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I ditched all the stock computer stuff on my 91 bronco Mexican prerunner. It had a issue with water puddles. Didn’t like them at all and I lost all faith in the antique computer and wiring.

Sooo.... I did a 4150 Holley 650. Way to much carburetor. I should have installed a 4160 (vac secondary) 390 cfm. It’s a mild build. Small cam, 9.5 compression, no smog clap trap, headers, alum heads and intake. It gets 7 miles 2 the gallon!!!

It’s a good thing I have a 45 gallon tank in it. Sucks to fill up ($$$).

I am wondering about a Holley 390 vacuum secondary carb. I don’t know if would improve this much. I am thinking that going from a double pumper to a vacuum secondary would help because it only gives/opens the secondaries as the engine can use it.

Bert, what do you think?

One time I pulled into la Paz after prerunninng from loreto to the finish for the 2017 b1k. Last gas was in comondu. It was about midnight and the old guy at the Pemex station in la Paz starting looking around on the ground for gas running out as he pumped past 40 gallons. It took about 43 1/2 gallons that time. I remember it was 3800 pesos. Things a pig.
 

Bert is my name

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A 500 cfm. Spreadbore will give good throttle response and still flow enough on top. Vacuum secondary will help with fuel economy. I don't know where you live. But, I highly recommend having what ever carb you use tuned by rick Walker in el cajon. Also look into having your distributor curved. A lot of power and drivability is left on the table when th distributor is not curved for your combination. Most off the shelf distributors come in way too late. Even a 650 vacuum secondary spreadbore will run good on most small blocks when properly tuned.
 

Bert is my name

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I think a 390 is too small for your combination. There are calculators on line to help figure it out. Vacuum secondary carbs are good for part throttle driving. Double pumpers are good for w.f.o.
 

partybarge_pilot

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I skipped the whole tuned stock computer on the old Barge. Went with a SDS plug and play set-up. IT was pretty primitive by today's standards, but way easier to work with than the factory computer.

It also go filled with mud a couple times do to my stupidity. Simple wash out with water and blow dry and it was back in action.
 

cjohnson

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Sooo.... I did a 4150 Holley 650. Way to much carburetor. I should have installed a 4160 (vac secondary) 390 cfm. It’s a mild build. Small cam, 9.5 compression, no smog clap trap, headers, alum heads and intake. It gets 7 miles 2 the gallon!!!
If you're running a 5L(302) the 650 might be a little big unless you're turning a lot of RPM. You can check using a vacuum gauge. At WOT you want manifold vacuum to be close to 0 but not zero. Around 1 to 1.5 HG is good. If it is 0 your carb is too big. If it's 2, 3, 4... your carb is too small. It's better to be a little small than too big. Especially if you're worried about fuel economy. 4 barrel carbs are rated at 1.5 HG and don't work properly without some pressure drop.

I think a 390 is too small for your combination. There are calculators on line to help figure it out. Vacuum secondary carbs are good for part throttle driving. Double pumpers are good for w.f.o.
I generally agree with this but you can get much better throttle response in race situations with mechanical secondaries(double pumper) if the carb is set up and sized properly.
 
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