98 Cobra Family Cruiser

[NXcoupe]

Ok, we need to get together and see what we can do to get it lined out for you.

[Rick93coupe]

That looks really really good man! The wheels are perfect!

[PKFIRE]

That car has such a good look to it!

[5.0calypso93lx]

Thanks guys! Got to enjoy the car quite a bit this weekend at the Milford Kroger cruise in and the Back the Heroes car show in Batavia:

[5.0calypso93lx]

Ok, we need to get together and see what we can do to get it lined out for you.

Thanks Mike! I have a new TPS connector I got on Friday that I am hoping I can depin the old one and install the new. Also have a new IAC on the way. Should be here Wednesday. Trying to eliminate the things that I know aren't good on the car and do a little maintenance.

[5.0calypso93lx]

Also if anyone knows of a stock OEM black 96-98 Cobra hood that is really nice I am looking for one

[5.0calypso93lx]

Put a new IAC on the car last night and also replaced the connector for the TPS. No difference in idle and still idling around 1200rpm. I need to find a good vacuum diagram and take a look at everything there next

[JIMS SVT]

Is it tuned?

[5.0calypso93lx]

Is it tuned?

It was apparently tuned before I bought it by STLMustangs HQ (I bought the car from a guy just outside of St Louis) for the emissions parts removal. Smog pump, egr, purge valve, etc. The previous owner told me he took the smog parts off the car because of "some emissions related check engine light". From my research that would make sense as the car has to be tuned to turn the EGR off. I also read that the Theft light flashing on the dash can be a result of the car being tuned or the ECU being tampered with in some way. It is the stock AOL3 ECU as I did confirm that last week. The more I dig into troubleshooting the car the more I think the idle issue is related to the emissions parts removal, aka vacuum leak somewhere, or the tune itself. The car runs fine and pulls good otherwise, but this idle / rpm hang issue is super annoying.

[5.0calypso93lx]

Found this ground strap attached to core support leading nowhere. Unhooked the batter while replacing the iac and found it:


This is unplugged back by the rear passenger side of the bay. I think it's the evap purge solenoid plug.

[redfirepearlgt]

^^^ If you are trying to identify a vacuum leak without a vacuum gauge, and you have a hand held programmer with ability to datalog short term and long term fuel trims you may be able to tell this way. Observe that LTFT's with the car idling. If there is a vacuum leak you have unmetered air. So the car will want to run lean. The ECM will see this and try to correct for it by adding fuel which can be seen in the STFT's and especially LTFT's. When you increase the throttle vacuum decreases (moves toward 0" Hg). As it does the trims will then correct again because the ECM will see AFR getting richer as the air coming in seeks the lesser route of resistance (TB is opening so engine is seenig more metered air) because the vacuum leak becomes less as throttle position gets closer to WOT. Ford describes this basic technique in their shop manuals.

Check the link out. Its for a 2005+ but it still tuning basics 101 troubleshooting for most modern day fuel injected cars.

https://iihs.net/fsm/?d=8&f=Adaptive...niques.pdf&p=1

Hope this helps.

[S281SC]

There is a vacuum port that goes to the passenger valve cover pcv valve. It is basically right under the throttle body opening on the intake manifold. This has a short rubber hose that has been know to come loose or deteriorate.


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[5.0calypso93lx]

There is a vacuum port that goes to the passenger valve cover pcv valve. It is basically right under the throttle body opening on the intake manifold. This has a short rubber hose that has been know to come loose or deteriorate.


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So I just had that off putting on the JLT intake. I am familiar with the older style pcv valves that was on the back of the intake manifold on my 1993 Mustang. This car has nothing like that (and it was like that when I got it in my defense). It's just a straight open fitting with the hose connected to it that goes to the intake tube. I will take a closer look. Do these 4v's have similar PCV's like what I had on my 93? Because right now I have just an open fitting.

[5.0calypso93lx]

^^^ If you are trying to identify a vacuum leak without a vacuum gauge, and you have a hand held programmer with ability to datalog short term and long term fuel trims you may be able to tell this way. Observe that LTFT's with the car idling. If there is a vacuum leak you have unmetered air. So the car will want to run lean. The ECM will see this and try to correct for it by adding fuel which can be seen in the STFT's and especially LTFT's. When you increase the throttle vacuum decreases (moves toward 0" Hg). As it does the trims will then correct again because the ECM will see AFR getting richer as the air coming in seeks the lesser route of resistance (TB is opening so engine is seenig more metered air) because the vacuum leak becomes less as throttle position gets closer to WOT. Ford describes this basic technique in their shop manuals.

Check the link out. Its for a 2005+ but it still tuning basics 101 troubleshooting for most modern day fuel injected cars.

https://iihs.net/fsm/?d=8&f=Adaptive...niques.pdf&p=1

Hope this helps.

That definitely makes logical sense to me. I do have a new SCT X4 so I will dig into that and see if I can't figure out how to view those tables. Thank you

[redfirepearlgt]

^^^ Download and install LIVELINK II (free down load) from SCT's website. Its free. This is a datalogging software package that will let you choose the PIDs you wish to monitor. Its actually easier than trying to configure the handheld IMO. Plug the tuner into the car, tether the device to your laptop with a printer USB cable (same cable you use to upload a tune into the X4), start the software click guide me, and follow the prompts. If you run into trouble call me one evening and I think I can remember how to walk through it though its been a while.

[5.0calypso93lx]

^^^ Download and install LIVELINK II (free down load) from SCT's website. Its free. This is a datalogging software package that will let you choose the PIDs you wish to monitor. Its actually easier than trying to configure the handheld IMO. Plug the tuner into the car, tether the device to your laptop with a printer USB cable (same cable you use to upload a tune into the X4), start the software click guide me, and follow the prompts. If you run into trouble call me one evening and I think I can remember how to walk through it though its been a while.

Thanks Chad, I am definitely going to try this.

Got a smoke machine on the car last night to check for any vacuum leaks. Besides the small amount coming out of the IAC vent I am seeing nothing. Everything is looking good there. I did get the rpm set to 600rpm with the IAC unplugged and checked TPS voltage. It's at .88 which I show is within spec. As soon as the IAC is plugged back in it wants to shoot up to 1200rpm at idle in neutral. This is with both the OEM IAC and a brand new Hitachi IAC.

I bought a little restrictor plate for the IAC and it doesn't help with either IAC either:


I do have a couple of codes, but 1 is for the TPS which I was messing with, 2 are for the purge valve which was removed and the other 2 are imrc related. After clearing all the codes the 2 purge valve codes come right back, but the other 3 aren't back yet, but still have the high idle issue even before the 2 imrc codes exist:



P0122 -> Throttle Pedal Position Sensor/Switch (TPS) A Circuit Low Input -> Had a busted TPS connector and replaced it with a new connector
P1516 -> Intake Manifold Runner Control Input Error Bank 1 -> Not entirely sure what the deal is here. Both sides spring open and closed fine and previous owner says that nothing with the IMRC's was ever messed with
P0443 -> EVAP Purge Control Circuit -> Purge valve is gone entirely
P1445 -> Purge Flow Sensor Circuit High Condition -> Same as above
P1519 -> Intake Manifold Runner Control Stuck Closed -> This is the other IMRC related code.

Chad, here is also a pic of the LTFT at idle. It definitely seems odd to me how high these values are. I'm not sure what the "acceptable" value of change is, but 17-23% seems really high to me.

[redfirepearlgt]

The LTFT's are high. That is correcting for the unmetered air getting in I suspect. I believe on an SCT 1.00 is optimal (no correction needed) where as on a Lund tuner device LTFT optimal is 0.00. If that number begins to drop as you increase throttle your EGR find is a good start. Delete the stupid thing. It is only there for NO emissions which only happens in lean (above lambda 1.0) with hot engine conditions. "Stick it to the man!!" as the liberal hippies love to say. Tear that thing off and delete it. Remember that at idle - the most difficult part of the tuning process - a little bit of unmetered air has a large effect. You are splitting hairs, even with a stock setup. It's the one of the two most time consuming and difficult parts of the tuning process. I never realized that until I read Greg Banish's book on tuning, and then comfirmed that with 3 tuners locally. I always like to discuss what I have read with the pros to know if what I have read is current and accurate.

Was not aware that IMRC plates were being used before 2005. Interesting. Those devices will also cause problems from reading about them. as I recall aside from sticking it seems that they can allow unmetered air in around the actuators IIRC - at least that has been known to happen on 4.6L 3V engines when they get miles on them. A lot of people eliminated them when they started turning on the power even at the earlier stages of upgrades.

[redfirepearlgt]

^^^ Stand corrected. SCT X4 will also show 0.00 LTFT's at optimal. Positive number indicates adding fuel and neg number means pulling fuel. Sorry for the confusion. Been out of it for a while.

[5.0calypso93lx]

Been very slowly working on this thing here lately. I wanted to fix a couple things that I knew were problematic and that's actually helped out in other areas. I was having issues where the car would completely cut out either going around turns or getting on the throttle when the car had under half tank of fuel. Got the tank dropped to find a On3 340lph pump in the tank. The car has a stock tune on it so what I think happened is that the pump burned up due to the variable voltage electronics this car has on it stock. My understanding is that a non-variable voltage pump will die quickly if it's not seeing full voltage, but a variable voltage pump will live just fine with constant full voltage.




Replaced the On3 pump and modified basket with a new Walbro / TIA Automotive 255lph setup from LMR.




Crazy how well the car runs when it's getting all the fuel commanded . I put a 1/4 tank of gas in it and went around some turns and no more cutting out. The idle is also significantly better. It is also making my clutch issue more prominent as a 3rd gear pull on the highway had the clutch slipping like crazy when I hit 4500rpm. That's the current issue I'm tackling and hope to have it replaced here in the next couple weeks.

Got started on the IMRC delete as well. The top two trans bellhousing bolts are super fun to get for the clutch replacement to so I decided that going ahead and pulling the intake mani to do the IMRC deletes. Big thanks to Jimsvt for his help throughout this and he was dead nuts on about there being tons of build up in the runners in the heads where the IMRC valves were. Hopefully pick up some power by just cleaning out each runner:

[5.0calypso93lx]

Pulled the trigger on a carbon LSB spoiler. I've got an authentic saleen, but the fit isn't quite where I want it and I personally really like the look of these newer LSB customs / GT350 style spoilers:




Unfortunately I found a crank in it and it's going to be sent back. Won't get another for about a month, but the guy has been great to work with and is sending out a new one no questions asked as soon as he gets them in. Sent me a prepaid return label and has been very timely with his communication. So far so good as long as I can get a good spoiler at the end of the day.