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New guy, and lost

3238 Views 85 Replies 18 Participants Last post by  JTX2
My son and I went to the drag strip with my father in law. Needless to say we were hooked. He’s always wanted a fox body, and it’s a chance to spend time with him, while i try to recapture my youth.
So we bought an abused/neglected 89 GT aod car. Partly being cheap, but also wanted him to learn about working on it. Also a good life lesson for him about what can happen to a good car if neglect and poor decisions about modification occur.
So, here’s what I think I know about it:
89GT car
Shorty headers and flow masters
Trick flow upper intake
BBK 75mm throttle body
Some janky looking intake tube with the stock MAF and a blue cone filter
Previous owner stated that he installed a F303 cam (no valvetrain mods)
Car seems to pull ok. But idles like crap. It will sit at 800rpm, then go up to 1300rpm on its own. Back and forth every minute or so. When it’s chosen the lower idle a high pitched whistle occurs. Sounds like it’s in the intake. I have sprayed brake cleaner all over it to see if it is a leak, but no change in rpm while doing so. When throttled in park/neutral, it’s reasonably responsive, but rpms are slow to drop back to whatever idle it chooses. I set the tps to .96v and it seems worse (it was like .40v)
Am I dealing with a throttle body/maf imbalance? A bad sensor in the system? Is the F303 install without valvetrain mods the culprit?
Any help you can provide would be much appreciated. Just not sure what direction to go. I don’t mind spending money on it, but don’t want to just throw money at it and still be in the same place.
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Please stop with the carb is better/faster/easier than EFI. Let’s just say if you enjoy carbs on a car you may be a dinosaur or from south the mason Dixon line. Who wants to deal with constant adjustments, cold start issues,hot starts stalls and all the other bs
Why do people always say stuff like this? None of my carbed cars have these problems. You just start them and drive them like any other car. You can't tell they are carbed unless you open the hood and look. I think there's a lot of fearing the unknown when it comes to carbs. The lack of throttle response in my EFI truck does get old though.
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Oh, the horror, part II .. The boat was fuel injected though......
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Leaking smoke during smoke test from tps and throttle body linkage is normal. Should hook up the EGR instead of deleting it. Some require tuning deleting EGR.
All the vacuum lines and vacuum tree on the passenger side firewall area are all the EGR and thermactors and smog equipment bypass valves vacuum lines and tubes. And your hvac control vacuum line comes from there too. The EGR has a lot to do with the way the car runs at idle at wide open throttle or normal driving conditions the ECU opening and closing it when it is commanded and why I recommend hooking it up or replacing it if it's not working. Not deleting it. Any emissions requirements where you live?
No emissions in NC. I am getting to the point of critical decision time on the fuel injection vs carb decision. The explorer throttle body and egr spacer should be here today. But I am already seeing possible complications with them. Such as linkage (especially for the tv cable), no pcv port, and gasket incompatibility with the trick flow intake. I have zero interest in spending several hundred dollars to find out something like the ecm is causing my issues. Don’t misunderstand me, I think fuel injection is better than carb. But not the crappy 33 year old eec system on these cars.
Your car already runs and drives you are way ahead of other people on their projects on that alone. The eec systems just need all the parts hooked up and functioning properly and then they work good. I got two of them that pass emissions every two years here in Denver which is a p i t a. An 89 and 91. Stock ECU stock wiring on both of them. The problem is the previous owners LOL. Or multiple's of them.
When buying an Explorer throttle body for a fox upgrade you have to stick with the 96' or early 97' with the GT40 3 bar heads. The throttle bodys and EGR spacers are different than a foxbody, no breather tube on the later 97' and up throttle body's with p heads unless you can drill and machine the breather tube hole yourself. The EGR spacers on all explorers are completely different from a fox.
Really the Explorer throttle body upgrade is a whole other project on its own set that aside for now because you use your linkage off your stock throttle body to put in that explorer throttle body that's how that works and you modify the shaft some for the bigger butterfly to fit.
Ok, so to give it it’s best chance at staying injected, I am installing a factory mustang throttle body and egr spacer. I do have to bypass the cooling lines though. The 75mm inlet on the trickfow intake isn’t compatible, gasket , to the factory sized egr spacer.
How do you plan on bypassing the coolant lines? Need to keep the coolant temp sensor in there. Maybe you mean the small coolant lines to EGR spacer. Which that wouldn't be a problem bypassing those.
This is a good assortment of gaskets to see if they can split the difference for what your trying to do sometimes a 70mm works with what I think your doing.
I just got done installing the tb and egr spacer. Battery disconnected per the advice further up in the post. How long am I looking for before reconnecting?
I think there's a lot of fearing the unknown when it comes to carbs. The lack of throttle response in my EFI truck does get old though.
I think fear of the unknown could be applied to those who don't like EFI, or have an issue they can't resolve. I had my car on the dyno a few weeks back, and the dyno operator commented that it ran like a well tuned carbureted car. Having a good running car that doesn't have any little quirks can be done with some work, either way you'll tinker with a carb, or a tuner.
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Not sure if the trickfow intake’s 75 mm inlet is the culprit, or if I got a bad stock throttle body (don’t see how one could go bad). But it ran like crap with a factory egr spacer and throttle body. Maybe previous owner had the computer altered to run the 75mm throttle body? I even did another smoke test in that configuration to make sure it was sealed up. I swapped my idle air control and tps sensor onto the “new” parts, no change.
So, I put the 75mm tb and spacer back on with the egr and coolant lines deleted (same way it was for the stock sized parts). The car went right back to how it was. I swapped the idle air and set the timing to 14 degrees and the surging appears greatly minimized. It won’t idle at less than 950 rpm on the factory tach. The extremely loud, high pitched whistling sound is almost constant now, at idle speed.
Not sure if I am willing to spend the money on a 75mm mass air, or use that money towards a carb swap. I can buy one of the two more expensive parts (carb or intake) with what it would cost to buy a decent 75mm maf
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Car is running like absolute garbage. I prefer not to hear any more people praising the efi system, it is absolutely garbage on this particular specimen. I am going carb and welcome advice geared towards that direction.
Did you ever check for codes?
one of the more competitive cars at the local track is a dragster (rail car). Typical 555" BBC, Powerglide. Runs on 100% methanol. But one of the big key takeaways is that is EFI. Nobody runs EFI in bracket racing to speak of except this guy, and it works excellent. Low fuel usage (well, for methanol anyway), idles cleanly, comes up on the stop clean, doesn't milk the oil, keeps a temperature, runs very consistent (and fast). it's a really nice setup. F.A.S.T system, although a lot of aftermarket systems can run it just fine. The Ford system could run it too assuming one could "teach it" that 5.5:1 a/f ratio is what is commanded. I don't know if that's possible.

My 92 Mustang is still running factory EFI as well. And it's a 427" SBF. It runs it just fine, but it MUST have a way to tune it. Originally it was a "calibrated" MAF setup and while it did start/run/drive, it was FAR from ideal. Tuning it, opens up a whole other world. But it's still a factory system which carries some limitations. That's where aftermarket EFI comes in.

On my race car (75 Ford Maverick), it was a carburetor for decades. It did the job just fine. In 2005 I put a mechanical injection on it (no electronic, all mechanical similar to sprint cars). Consistency came around, and it began winning LOTS of races. In 2007 my little program won 37 rounds straight which nobody has done since to my knowledge. I had it down, I worked, the car worked. The last 3 rounds the converter was going away but I was NOT about to let a failing converter ruin the streak. In the final round the stall speed was north of 7200. Couldn't feel or detect a shift. LOL! Pulled it afterwards, sent it out, completely rebuilt the transmission as it was trashed as well. Never really got back to full-time racing as in 08 I got the invite to go to a bigger team. Got my comp license and went for it. Sponsors pulled out a while later and from then on our programs mostly sat. Anyway last season I had to completely re-wire my Maverick and in the process I converted from distributor to sequentially fired coil-near-plug. It doesn't go any faster but it IS a little more consistent and it also is a LOT smoother running. With the cam and mechanical injection, smooth running is of no concern but it does make it easier to stage against the converter (footbrake) which allows for a little more consistency. I'm running 5.70's at 120-121 in the 1/8 with it. Biggest thing (for me) is consistency and normally the first time trial is my dial in for the rest of the day. VERY predictable. The car has a little more in it but it doesn't need to go any faster. Not in this car. It's been low 5-teens at 140 in 2011, with a different setup, and that was sketchy.

carbs can and do work. But they aren't bolt-ons, you still have to tune them. Most carbs are running richer than they need to be. In bracket racing our little Ford's, I find that running them LEANER seems to work best. Not too lean, but leaner than "ideal". Helps with weather changes. EFI can work too and it often does. My 92 GT doesn't go to the race track but it could. I just choose not to, other than to go watch.

I also own an 85 LX coupe which is slowly getting reworked. It is also a race car and has been for a long time. Nothing special. It's getting a 5.4L out of a Lincoln Navigator, Sullivan intake, and will be mechanical methanol injected. Powerglide transmission. I don't think anyone has ever done it but I am. Biggest thing is controlling spark since they don't have a distributor, so I'm currently looking at that and there are a lot of options. I'm "hoping" to see it run in the mid 6.30 range in the 1/8 mile. It may not ever get close but I'm certainly going to try. What I've learned about these modulars is that they are really really expensive. The 4 camshafts alone cost as much as some SBF aftermarket aluminum the chains, custom pistons, head porting, valve job, custom headers, etc. I originally wanted EFI but I think MFI on methanol is a better option for what I want to do with it. It is MUCH simpler (simpler than carburetors) and usually more consistent.
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For less than $100, you could get the EFI going. The BBK whistle can be eliminated or at least greatly reduced by rounding the edges of the idle ports (BBK Throttle body whine/ high pitched noise fix). Clean the MAF. Check to see if it's chipped. Clean the IAC. Set timing. Make sure the TPS is good (the reading you got of .04 VDC is tough to get to on a stock TPS). Fix every vacuum leak and hook up the EGR. Throttle body shaft leaks are ok as long as they are minor. Take all the money for the carb swap and spend it on gears, converter, and Bauman shift kit.

Or go carb. Think you had your mind made up before you came in here. You still need to deal with the F303 and stock head problem. Stock springs are right at coil bind with the F303. Cam and heads are mismatched. With the carb, you can straighten out the idle but it will still be a turd down low.
Did you ever check for codes?
I did do the key on, engine off (my daughter is sleeping right next to where I am working). I got the following:
29- no continuity in vehicle speed sensor circuit (my speedometer doesn’t work)
31- canister or egr valve not operating properly
(Car doesn’t have a egr anymore)
85- canister purge circuit or transmission shift control circuit

Here’s the great part:
My maf wasn’t even plugged in. After the test I remembered that it was on the workbench from cleaning it (nothing was on it, but sprayed it anyway).
How awesome is this system! The computer didn’t even recognize that the maf wasn’t even on the car!
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