MSefi.com read only forum (Jan.15,2018)

Hey guys,

I'm new to the MS community and I am having some trouble with my new build. After I got everything wired up and checked for leaks I tried to start the truck. After a couple of backfires and small fires in the throttle body it starts up but goes straight to redline. I currently have all the vaccum ports blocked off except the one going to the MAP sensor on the MS. I checked the wiring to the IAC and I think I have it wired correctly, but I would like to know if the stepper IAC is full retracted would that be enough air to allow a redline rev. Below are the specs to what equipment and software I have.

1989 toyota pickup w/ford 302 v8
1992 GM TBI wit 55lbhr injectors
MS 2 w/ B&G 2.905 firmware
not tuned just trying to get to idle.

Thanks for the help guys.

I doubt seriously that a stuck/retracted IAC would cause this problem. IMO it would take a lot of air to act like an open throttle. I understand that you have plugged all vacuum ports, etc.
How about intake manifold, tb base gasket etc?

I know all of this seems remote but I assure you, I have seen stranger things.

Well that's what I was thinking, but also I set the parameters for everything as listed in the ms2 megamanual and also watched the video on DIY autotune website. I wouldn't think it could get enough fuel to rev that high but it does. I had to change the fuel cut to 2000 rpm just so it wouldn't run away. It does backfire and flame up in the throttle body. From what I understand is the injectors are adding to much fuel if thats happening. Also this is a fuel on set up right now, because the truck runs ok with the carb. The only reason I'm switching over is because I climb with the truck and the carb is starting to give me trouble on the hills.

Could you post a data log of this behavior and a copy of your MSQ?

smokey212 wrote:Well that's what I was thinking, but also I set the parameters for everything as listed in the ms2 megamanual and also watched the video on DIY autotune website. I wouldn't think it could get enough fuel to rev that high but it does. I had to change the fuel cut to 2000 rpm just so it wouldn't run away. It does backfire and flame up in the throttle body. From what I understand is the injectors are adding to much fuel if thats happening. Also this is a fuel on set up right now, because the truck runs ok with the carb. The only reason I'm switching over is because I climb with the truck and the carb is starting to give me trouble on the hills.

Simply adding more fuel won't make it rev higher - unless it is getting air too. Which means there must be a massive leak somewhere after the throttle valve - or that is sticking open.

From what I understand is the injectors are adding to much fuel if thats happening.

Simply not correct.

trakkies is 100% accurate on this!

As he pointed out, excessive fuel, generally will not cause the engine to rev higher. (unless of course it was lean to start with) Quite the opposite actually. Usually too much fuel will cause it to slobber and eventually die.

You may be getting too much fuel but you certainly are getting way too much air from somewhere! It is fairly easy to find air/vacuum leaks with carburetor spray, so you might want to give that a try! But that could be tough if you can't get the rpm down to something reasonable.

As Matt suggested, a log and msq would really help.

Ken

Thanks for the help guys. I think I have the right files you wanted Matt. I agree with you guys that it doesn't seem right that it would run really high without getting the right mix of fuel and air together. I am an old school carb guy so I'm having to adjust to the computer controlling fuel input. Just to give you guys some extra information about the build i'll list how I have it wired. I am using the relay board from DIY autotune, I built the ECU myself and tested with the stim. It worked on the stim as per the build manual. I'm using a MSD 6al to control timing and I have the Tach out wired to the MS for the tach signal. I started the truck while I still had the carb hooked up to check the a/f ratio's and RPM and all other sensor etc. It seemed to show a clean tach signal and all sensors were working as designed. Like I said before when I started it with the TBI if backfires through the TBI and I even had a small fire a couple of time. Nothing I didn't expect or have seen before. It does start, but that's when I get my high rev issue. I had to set fuel cut to 2000rpm just to see if I could figure anything else out. It doesn't have any other tables tuned etc.

Even in my amateur observation of your log I am thinking that you may have a combination of several things going on here!

On start your PW jumps to ~29ms....... at another point RPM spikes to ~22,700.....

I know nothing about MSD but I am guessing that you have an ignition issue going on here, at the very least. So..... lets see what Matt and the other guys with the really big brains make of this!

Sorry for not being more help.

Ken

Ken, what program are you using to look at the code? I have C, and assembly language access through school. I'm an electrical engineer undergrads student.

smokey,

I'm looking at the msl that you posted, using MLV. There is no need to get into the code!

I suspect that Matt and some others will have some suggestions (and questions) when they look at that log.

Ken

So I just downloaded MLV to take a look at the log myself. It looks like my settings didn't save when I was configuring my setup before start. I always wrote to the controller before I exited the tab and it said settings were burned. One think that did keep happening was TS would crash my computer to the blue screen of death. I think I'm going to reload TS also. I'd like to eliminate any variable in the software. I'm thinking about purchasing the registered version of TS. Any perks to that?

It looks like my settings didn't save when I was configuring my setup before start. I always wrote to the controller before I exited the tab and it said settings were burned.

I'm speculating here, but I suspect the issues with MAP never dropping below ~99 kPa and the rpm spiking to ~22,700 are more than just settings.

One think that did keep happening was TS would crash my computer to the blue screen of death. I think I'm going to reload TS also.

What version of TS are you using?

I'm thinking about purchasing the registered version of TS. Any perks to that?

I certainly would recommend it!!! The VE Analyze Live function alone makes It worth twice the purchase price IMO.

Just curious..... Have you tested your MS on a stim?

Ken

Yes I tested it on the 5 pot stim and it worked as described. I did put it back on the stim after I had the start issues and the only thing I noticed is that the injector LEDs did not slow down when the TPS pot was all the way down like it did before I hooked everything up to the vehicle. I didn't know if that was because I had already configured it to the truck or what. I haven't gotten any farther since then. Other than talking to you guys.

Ok, I found the problem. A while back my truck had a small fire under the hood. It didn't burn everything but it did get hot. It must have warped my intake manifold a little because it was pulling air underneath the tbi adapter plate. One gasket was not enough to seal it up so I tried an extra one. I then went back over the configuration in TS and it fired up and idled. I bumped the VE table cells up a little and it smoothed out. Now on to tuning. Thanks for the suggestions guys. I have some pictures if anyone is interested.

had a small fire under the hood

I guess that would account for the nick "smokey" huh?

Glad to see you found the problem!

Ken