weird fast idle problem when driving (fixed thanks to moates quarterhorse + tunerpro)

[rockerZ71]

Today I took the day off work and rode over to harbor freight this morning. On the way back about half way home my motor was going to up around 1500-1700 rpm when I'd push the clutch down at stop lights etc. I thought the clutch sorta felt weird at one point but that could have been my imagination, it didn't happen again. I pulled in at the UPS store to drop something off and turned off the truck. When I started heading home I thought it was all OK because the first few minutes I didn't have the problem, it would idle down as normal (It has always seemed to take a little longer than I'd expect to slow down after I push in the clutch and the previous owner thought so too, I bought this quarterhorse programmer I have been intending to install at some point to try to figure out /address that problem) but then it started doing it again. Noticed as I was about to pull in the neighborhood that if I just pushed the clutch in and coasted it would idle down, but if I pressed the brake pedal it would rev right back up to around 1600.

Looked under the dash and noticed that one of the 2 wires going to the brake switch was broken. So I just fixed that and have not yet driven it. Maybe that has something to do with it and it'll be fixed, but regardless I'd like to understand the problem as I don't see why that would have anything to do with it and if it doesn't I've got a real problem I need to get figured out.

The motor is a 302 w/ '93 cobra EFI. 3speed transmission

 

[Viperwolf1]

Make sure the throttle cable isn't binding or adjusted too tightly. There should be a little slop in it at idle. The firewall can move slightly when the clutch is pressed and that can translate in throttle movement in the cable.

 

[rockerZ71]

Re: weird fast idle problem when driving

Yeah theres slack in the cable

Sent from my SGH-T889 using Tapatalk 2

 

[rockerZ71]

It ended up being the TPS. Probably just needed to be cleaned, but a new one was $35 which was quicker and easier than messing with the existing one.

Figured it out by installing the quarterhorse I had sitting around for a while, I used tunerpro and made some dashboards and graphs after a bit of research into how it all worked, noticed that the throttle position voltage was fluctuating a bit a lot of the time without me touching the throttle. Put on the new one and its right at .98 until I touch the throttle.

Really glad I got the quarterhorse - would've had a hard time figuring it out otherwise since it was an intermittent thing. TPS makes sense but before this I'd have expected it to be sticking or something like that, not fluctuating. This takes all the guess work out of it.

 

[xcntrk]

How do you like the QH product and what other tuning do you have planned with it?

I have that purchase slated as well. Of course I need to convert to EFI first ;D

 

[rockerZ71]

How do you like the QH product and what other tuning do you have planned with it?

I have that purchase slated as well. Of course I need to convert to EFI first ;D

I love it. Installation was quick and easy and the cost wasn't bad - around $250 IIRC.

Not sure what else I have planned as far as tuning goes but I have been reading more and more about it and as I learn more I'm sure I will mess with the tuning even more. Initially bought it because it seemed like it took too long for the motor to idle down after releasing the gas, like if I'm going 60mph and push down the clutch and let off the gas it would stay at high RPM longer than seemed right. I ended up fixing that easily in the process of figuring out this problem, although it had nothing to do with the fast idle issue.

It seems like most people pay up for binary editor/EEC analyzer but I downloaded them and tunerpro and I like tunerpro much better and don't see what advantages the others have. Maybe there is some but I think I can do everything I want with tunerpro and I like the way its set up. I don't care for the interface of BE, but then again I never actually used it. Tunerpro RT is free to use full-featured but if you don't pay to register a window pops up at the start for 10 seconds asking you to register. I paid the guy the $39 for his hard work on it and to get rid of that window. The interface to make dashboards could be better/easier and there are some improvements I'd make to the graphs and stuff but it works fine and the graphs and dashboards are very useful and look fine as is (once you put enough effort into tweaking them the way you want)

I write software to control broadcasting equipment for a living, and after looking over how the software communicates with the QH it is really similar to what I do every day, so I am starting to work on software to read it from my phone so I can at least log and display live data on my phone (which I use as a GPS and music player in the bronco so its mounted in a convenient place). Also I emailed the QH developer and found out about a header on the board that provides another serial interface and got a bluetooth transceiver for $10 I'm going to have a friend soldered up so hopefully I will be able to log data without the usb cable

 

[xcntrk]

Good stuff! Any idea if the TunerPro has the ability to accept additional data feeds, such as W/B AFR, and incorporate into a common dashboard or logger needed for true EFI tuning? As for tuning uses, I was looking at QH to manipulate MAF scaling and modify ignition table.

 

[rockerZ71]

Good stuff! Any idea if the TunerPro has the ability to accept additional data feeds, such as W/B AFR, and incorporate into a common dashboard or logger needed for true EFI tuning? As for tuning uses, I was looking at QH to manipulate MAF scaling and modify ignition table.

Yeah you can download the files that define the data acquisition scheme from here
http://support.moates.net/ford-tunerpro-definitions-for-quarterhorse/a9l-gufb-tunerpro/

the adx file shows the protocol and command sequences being used, but you can just load them up in tunerpro to check it out. Theres something called "wideband LC1 on EGR" built in there so if you can wire it up that way it should work, or I guess any other available input (sensors the ECM supports but you don't have) would work.

Really there is no need to have the sensor wired to the ECM but the software as far as I can tell only supports polling data from a single interface (unless these adx files provide more flexibility than I think they do, but theres no documentation for them as far as I can tell and I doubt it) - I'm sure a plugin for tunerpro could be written fairly easily that acquires data from multiple sources at the same time and not just from the connection to the QH.

 

[rockerZ71]

well that link above assumes you have the same type of ECM as I do, if not you'll have to find what works for you. Mine is from a 93 mustang

 

[xcntrk]

something called "wideband LC1 on EGR" built in

Yeah that's it. The LC-1 is the Innovate Motorsports AFR monitoring product. So it sounds like plug n play if you use that product.

Sweet! Now I just need to install all my EFI parts ;D

 

[rockerZ71]

Sweet, hit me up if you have questions about the QH or tunerpro, I'm no expert yet but I'm happy to help if I can.

And yeah I found that on amazon seemed to get really good reviews and is relatively cheap so I will probably be getting one.

I'm looking to start building another EFI motor myself, probably very similar to the one I have, just because I know nothing about building a motor and would like to and it'll give me an excuse to get maybe another bronco or 60's mustang to put it in eventually