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

I have a 1.3L Triumph Spitfire engine with MS-II V3, Ford EDIS ignition, 14# injectors and a Ford Escort (1.9L) throttle body with PWM for IAC.

The car has run with the MS-II controlling the ignition only, and now I have added a 4 port injection manifold to do the fuel side.

This is my first attempt at tuning anything and I'm looking for advice as to where to go next.

The car will start, but with difficulty. I get a lot of what appear to be single cylinder ignition, enough to kick out the starter bendix, but not enough to get sustained running. After a great deal of cranking I can get the engine to start, but the RPM rapidly goes to approximately 5000 for a few seconds and then just about as rapidly decreases and the engine dies. The AFR goes toward 18:1 as the engine dies. It almost appears as if something is cutting off the fuel.

I really don't quite know where to go next.

I've attached a copy of the latest tune configuration and a datalog of the last run.

Any suggestions would be greatly appreciated.

OK, I've solved part of my problem. I had the WUE configured to go below 100%, which was probably why the engine died. When I fixed that, it now stays running, although still at 5K+. I've attached a copy of the latest tune configuration.

Bill

Bill,

You have a vacuum leak. This causes the rpm to rise very high.

Unlike a carburetor, the engine doesn't go lean, because the controller compensates for the extra air, and as a result the engine speed gets very high.

The vacuum leak might be a missing/leaky hose, a bad, backwards or missing intake/throttle body gasket, a stuck or badly adjusted throttle stop, or a mis-adjusted or mis-configured idle valve; among other things.

Lance.

Thanks, Lance. It's odd you should mention a vacuum leak. When I first attempted to start the engine, I could get it to run briefly at about 500-550 rpm, a nice idle speed, but the AFR would rise up to about 16, at which point the engine would die.

I snugged up the bolts holding the intake manifold to the head a bit and then the situation changed to the present. What you are saying makes sense, and I have been wondering how the engine was getting the air to run so fast, since the throttle plate is completely across the throat of the throttle body when the throttle is closed. There is a new gasket installed between the throttle body and the manifold, torqued to the specs shown in the Ford manual.

I have wondered about the idle air valve. It's a standard Ford unit and I'm a bit uncertain as to whether 100% is fully open or fully closed. I THINK I've understood from the manual and this forum, that most likely 100% is full open. This would seem to be a likely area with which to experiment.

Thanks for the help, and I'll report back.

Bill

There is some progress to report. Following Lance's suggestion, I made SURE all the connections to the intake manifold were tight. Checking the Chilton manual for the Escort engine reveled that the fuel pressure regulator should maintain operating pressure for at least a minute after the fuel pump shut off. Mine was almost to zero pressure within 30 seconds or so. A replacement fixed that.

Now the engine will start, with a bit less cranking when cold, and virtually instantly when warmed up. The problem is that it won't STAY running without constant movement of the throttle. If I take my foot off the pedal, the rpm drops to about 500-600 rpm, and then the AFR goes to about 16 and the engine dies.

I think I'm getting closer, but I'm not there yet. Any suggestions as to what to adjust would be greatly appreciated.

Thanks in advance.

Bill B.

Bill,

Odds are that the constant little throttle movements are adding accel enrichment, and this is keep the engine running. That means the idle area of the VE table (i.e. those cells are low rpms) is likely too lean, and you should bump them up.

If this was mine, I would increase all the VE table values below 2000 rpm by 10 or so. Then try to start it and tune the idle for minimum MAP as described in the manual. You may have to increase the VE values even more, or it is possible you might have to reduce some of them.

Lance.

Thanks, Lance. Right now the VE table is whatever Tuners Studio made it when I downloaded the program. I've attached a copy of the current tune. I've been playing with the warm-up enrichment and the PWM idle control, so those tables look a bit weird. Those changes have not had much effect, and this is probably why.

Bill

I've now got the car so it will idle smoothly at about 650 rpm with no additional throttle movement required. The cold start still requires a bit of additional throttle to keep it running, so I may have too much WUE set in. Once it warms up, it idles nicely and re-starts quickly.

At idle, the AFR is about 12.0-12.3, so I'm thinking that it is still a bit rich there. I am guessing that the target AFR at idle would be something around 13.5-14.0. I assume to get there, I would decrease the value in the VE table cell where the idle occurs and then 'smooth' the values of the adjacent cells. Am I correct so far?

I've set the EGO authority to zero (0) so that should not be interfering with the tuning of the VE table. The accel enrichment is set at 2500 so as long as I keep the rpm below that, at least initially, that should not confuse things either. Am I still correct?

The next step from here is presumably to drive the car slowly, keeping the rpm low, but allowing the MAP to increase to allow adjustment of the VE table values further up.

Thanks, again for the help.

Bill

Based on what I've read, some engines do prefer richness for a good idle -- so don't be surprised if 13.5-14.0 is too lean. And remember, a lean misfire will cause the WB to read rich due to unburned fuel from teh misfire.