I'm having problems with my car that seem to be a combination of MAF and PROM issues.

Since swapping to the 165 ECM, the car was acting a bit flakey. At the time I was running a slightly modified APYP. The only changes I made were basically to the injector & fan turn-on constants. When I started it, I had to give it some gas and hold it at 2k rpm for a minute or so, otherwise the car would stall and die. Once I held it there for that minute or so, I can get off the gas and it'll idle ok.

So anyway... fast forward a little ways and I throw in the wells MAF to replace the stock 85 MAF (Remember, this is a 165 ECM I'm using). So anyway, with the Wells all seems to work the same way.

So the other day I burn a new chip. Still the same as the old one except that I bumped my injector constant up because my block learns were at 108. Start it up and it seems to behave the same.

A day or two later I parked it and the car wouldn't restart until today. Well, it would fire, but then die immediately. I put the Bosch sensor back in and it would start and stay running with my throttle input.

So I decide to burn a new chip to see what sort of difference it makes. This time I use an ANZA bin. Again, the only changes I made were to the injector and fan constants. Car starts, and requires the same sort of throttle nonsense. Once it idles on its own, it seems to idle smooth. oxygen sensor numbers look good... but it won't go into closed loop. Pop the APYP back in, wait a few seconds and it'll go into closed loop.

Part of what boggles me is that the APYP shows a block learn of 118. I pop the ANZA in and it shows 126. Shouldn't the block learn be staying somewhat constant and changing over a period of time? I change the chip, start the car, and bam! Different injector constant. 118 with the APYP and 126 with the ANZA.

Anyway, my questions are whether or not my starting problem could be PROM related, and if so, what do I play with to help eliminate it, and secondly, I just wanted opinions/ideas on the open loop behavior of the ANZA and my block learn numbers. Thanks.

 

Your problem is a combination of Startup Fuel and Open Loop Fuel.

A wide band O2 would save you so much time and guess work.

Using your scantool(diacom, ease, whatever). Before you start the car, connect to the ecm and see what your coolant temp is. Start the car and see how it runs(either too lean or too rich). Then go to your start up fuel vs. coolant table and add/subject accordingly.

From what I've seen, its usually the start up fuel that is the problem.

 

Does startup fuel effect the car after it initially fires?

If so, should I be adding or taking fuel away?

 

Start up fuel will affect the engine for the first few seconds of running. Since you are opening the throttle to get it to start, add fuel. See my other reply in your other post about the problem you are having.

Out of curiosity, have you tried another ECM?

 

No. I've had no reason to suspect that the ECM is faulty. I suppose I could pull the one out of my GTA and swap it though.

 

Tonight I modified the crank pulse vs. coolant temp table like you suggested. The car seemed to be a lot closer to staying running on its own, although it was still garbage until it warmed up. I still had to hold the throttle at 2k. If it fell below, it wouldn't stall as easily, but I had a bastard of a time getting the rpms to come back up.

It really seems to need more fuel until it warms up. Instead of adding more to the crank pulse, I was thinking about targeting something more long term, like maybe the open loop fuel/air ratio % change vs. coolant temp. This should fatten it up more until the car goes into closed loop. What do you guys think? Does this sound like a good thing to try, or am I barking up the wrong tree?

 

Yea that is the table you should edit....put the pulse vs ct table back to stock and mod the open loop fuel/air ratio % change vs. coolant temp table. You got rid of the CS injector too correct? Try scaling the values by 1.2 and see if it runs better. The reason for the different blms between chips is, you said it yourself, one chip is stuck in open loop and the other is going into closed loop. Blms are not updated in open loop.

 

The startup stuff is only active while the RPM is less then 400.
The crank pulse routine is based on the number of ref pulses.

From first run to actually running is about a .1 sec.. So the crank stuff has to supply just a tad extra fuel over the amount to first run the engine.

 

Thanks for the info guys. Tomorrow I'll try and play with the open loop table and see what happens. I'm happy to say that I finally found an injector constant that keeps my BLMs where I like them. Now if I can just get it to run on its own when it's cold, and get rid of my gross lack of low end power, I might like the car.

 

I'm about to burn the chip and this just dawned on me. Isn't this going to fatten me up at WOT too, or does the ECM go on the accel. enrichment tables for that?

 

that didn't work. I fattened the open loop pulse width vs. coolant temp table by using values 120% of the originals. I still needed to nurse the throttle and hold a higher idle, but now it ran rich as it warmed up.

Another thing that's bugging me, and I'm not sure if it's related or not, is how long it takes to get into closed loop. Once it warms up and gets into closed loop, if I shut the car off and restart it, sometimes it goes back into closed loop almost immediately, and other times it takes up to a couple minutes or more.

My IAC counts seem to be all over the road map too. Sometimes while I'm holding it at an idle above the desired idle, they are pegged at 160. I've had stupid IAC numbers right from day one dispite having a brand new TB, brand new IAC, I tested the ECM and IAC wiring, and reset minimum idle 50 times.

I swear I'm about ready to swap to carb.

 

Have you check for the vaccuum leakes?

 

I checked the vacuum and it seems to be fine. It pulls 16-17" of vacuum at idle, and there are no leaks that I can find. 10 or 15 minutes after I shut off the car I can pull the line off the reservoir and it still sucks air in.

 

I sent you mail....

 

I still didn't get it yet. Hopefully soon.

 

Send me a scan and a copy of the bin you want to use ... mail me at lrnelson5669@comcast.net

 

you have mail

 

have you solved it?

 

hell no. I've had the problem for a year... I don't expect it to go away in a day.

Slow was nice enough to modify my latest bin, but his email didn't come in until after I went to bed so I haven't been able to try it yet. When I get out of work I'll burn the one he did and see how it goes.

I really think my problem is more equipment related and less tuning related, but I'm definately willing to try anything. I really think I'm still having IAC issues. If Slow's chip doesn't work, I'm going to swap my ECM with the one in my GTA, and if necessary, I'll swap throttle bodies too.

 

A couple of things may be in the works here. Isn't the '85 MAF a frquency MAF, and the one used or the'165 APYP a voltage based MAF? A freq based MAF sorta' works on a voltage based input as the freq gets integrated into a voltage.

As for the strange IAC double check the ECM wiring of the battery feed (as oposed to the ignition feed). If the battery feed is switched off with the ignition the ECM can't do an IAC reset and park on power down. So it loses track of where the IAC really is.

RBob.