Ok here we go:
First of all, the Ostrich has been in the truck for about 3 weeks now and I love it. I have put 4 tunes in it messing with the idle/part throttle tuning so far, so much better, got it idling at 625, more part throttle response, etc. So about 5 days ago, I loaded a new tune up to the Ostrich(speed density). Everything seemed to be going smoothly....the engine was warm and ran great. So, in that tune I messed with the BLMs a little and changed the XDF file on the SA(spark advance) to read 0 so that whole numbers would only come up. At cold start up the next morning, once it warmed up a little and the idle started to drop and go into closed loop.....bam.....misfiring, rich eye burning smell, rpms fluctuating, etc. Well, I wrote it off as just it trying to learn the new tune. Few days went past, cold start was fine, barely did it somedays and warm start was good as it was not the problem. Now again, its misfiring, etc enough to now shut the engine completely off and backfire. So, 2 days ago, I load the custom tune I had from LSRacing back on there(by Tunerpro) and its still doing it. I'm about to pull the Ostrich and put the LSracing chip to see if that will solve anything thinking maybe the box got grounded or something. Anybody here have any input on this, I would appreciate it. I'll let y'all know later tonight whether it is still doing it with just the chip. The only other thing I can think of it could be is the heated o2 sensor is not reading right in cold start up. But while its warm, it does just fine and runs as it normally would. So, I am at a loss.

Thanks for the help!

Problem is fixed....cylinder head had a crack leaking coolant into the cylinder and cooling the fire.

 

Ok, put the stock chip b/c in it and its still going it. Now, I found a problem I think. Loop Closed Enable Min. Temp was at 20* C and I never changed it but I've looked at it quite a few times and remember it being like 56*. So, I'm going to change it to 50* and see what happens.

 

Ok made some more progress checking things out but nothing. Changed the Closed loop setting so it will be in open loop all the time, no effect. Took the ground off the battery and let everything reset for about 5 hours.....nothing. Looking at getting a computer from the junkyard and see if that helps.

 

Did you change that zero back to the original setting?

 

Yes, I downloaded a new unmodified xdf file from moates.

 

Just put new MAP, CTS, MAT, and cleaned/tested the IAC for trouble and tested the TPS. Still the same results so looks like a new computer is going in. Anybody else have any ideas?

 

I'd also verify the ignition module is good, they will act up this way sometimes when they warm up, but it's not often the same time as it goes closed loop. And you have reloaded the same BIN that was working fine before, right?

ANy data log showing it acting up? Maybe someone can spot an odd sensor value and help you zero in. Are you using a heated O2 sensor? And has the ambient temp changed from when it was working to now not working?

 

Ign. module seems to be good. Stock bin, LSracing bin, my custom bin.....all the same.

I put a wideband on it and it shows it going lean. I do have a heated 3 wire o2. Thinking it might be o2 related still considering we disabled it. Maybe the ground is bad. Amb. temp is changing as always right now but doesn't matter what temp it is, it still does it.

 

You disabled the O2 sensor? No way it can run decently like that unless you've tuned for strictly open loop and are running open loop. Any data logs?

 

Yea, I was in open loop. Just figured out that my adj. fuel pressure reg. from Holley is messing up something awful so I am going to replace it first and then seriously check the ign. module. If that's not the problem, then I have no clue.

The AFR ratio in open loop idle was 13:1. I need to lean it out some as well when I get it running right.

 

Ok, update.

After replacing the ign. module, fuel pressure reg. it still did it. So, I took off my Jacob's ign. box and ultra coil and fixed the problem for the moment. I'll let y'all know for sure.

 

Sounds like you may have found your problem. Sure hope so!!!

 

I surely hope so Vernw. Its been a big pain but I got extra sensors now so....I guess that's a good thing.

Anyways, ran great today...needs a little fine tuning but it was a combination of my Jacob's ign box and the min air setting. I had the min air set but it didn't like it. I also leaned out open loop idle a little bit and that seemed to help out as well. I'll keep this going tomorrow after I try out some more stuff.

 

Keep us posted, we all love to see gremlins found and eliminated

 

Ok, well, its stopped backfiring now but it still likes to surge or keep a high idle. So, after disconnecting the coil and and hooking one up at a time and taking them off and changing it around a bit, I think the distributor is bad b/c it does it with the tach plugged in or the Ultra Coil plug in so....we shall try that next.

While I was at it, I check the ohms on the injectors, everyone of them was right on 16.5(they are delphi 32 lb/hr).

 

Borrow a good distributor and drop it in. I had a similiar problem and that cured it. Drove me nuts for a while. I changed alot of parts before I found the problem.

 

Yea, I have a brand new one sitting on my toolbox but I ohm'd everything in it yesterday and reset some sensors so, we will see how it does today. The pickup ohm'd 910-920 so...its supposed to be 800-900 or so so it wasn't that much off.

 

New Distributor, new fuel pump relay, and changed idle/iac/AF ratio in the tune. Still.....nothing.

 

Ok more info to this:
I just changed spark plugs since it started doing it with these old plugs I put in about a month or so ago. Vacuum at idle is 19"mg at 625 rpms in idle, 17" in Drive at 575 rpms. Compression test came back great, everything was mostly 200 psi with some 202, 205, and a 210 mixed in. So, compression is within 5% which is good. So, messed with a few wires and rerouted some. I'm going to try it later tonight. If this doesn't change anything then IMO its injectors or the tune somehow needs to be changed b/c the engine changed somewhere.

 

Man, you've thrown just about everything at it except injectors! I'd see if someone has a spare set you can borrow/use for 2 or 3 days before buying them if possible. Just in case that's not the problem (unless you plan to need bigger ones anyway in the future).

Since you've got the Ostrich, have you tried real time changes to spark and idle fuel? Just a thought, but you've probably already done that. And gone back and re-checked the firing order and connections , etc.....

 

Go through and wiggle each wire at the ECM to be sure you have good contact. Sounds like something intermittant like that.
Could be water in a connection or something not touching "enough".
You fiddled with the ignition and it ran good, any wires there that were changed at the ECM or something like a loose memcal etc.?

 

Yep...everything tripled check. I have messed with teh timing, IAC setting, idle rpms, and fuel.....nothing so far. Seems like everything is pointing to injectors. Only thing that is not replaced is fuel pump, injectors, and the engine. All fuses are good. My injectors are Delphi 32 lb/hr that are not but 2 years old.
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I will check the wires at the ECM wiring harness but the memcal piggyback, etc is all good and tight. All grounds, etc are good as well.

Its been one heck of a time figuring this one out for sure.

 

What's your fuel pressure? Did you install another Holley AFPR or repair it? My Holley AFPR sucks, leaks fuel, doesn't hold pressure after Key Off.

 

Its a Kirban unit. Steady at idle at 34 psi and WOT at 43 psi.

 

That might be at least part of your problem - the fuel pressure. That sounds awfully low, frankly. Did you set it by disconnecting the vacuum line and then plugging that line while at idle? It should be set to 43 PSI at idle with no vacuum line connected. Mine idles more like 38-39 or so when the vacuum line is connected. Yours sounds a lot lower than that. Could be the difference in our motor's vacuum they pull at idle though.

 

Yes...vacuum line disconnect reads 43 psi. I have 19" of vacuum at idle too so I know its more then what you have vernw with the cam in your 383. My cam is just a 218/224. I'm leaning more towards my cam lobes might be worn or my lifters. I'll be checking it this weekend when I pull the intake off. Coming to the end of things it could be.

I will double check the 43 psi reading but I that's where and how I have always set it.

Ok....just checked it......now I am reading 31 psi where it was at 34 on Sunday. So, either my fuel filter is already clogged(3 months old) or my fuel pump is not flowing the volume.

 

SOunds like you're "right-er" than I was, sorry.

 

Hey man...I'm open to all answers so, not a problem. Anything else you can think of. Intake comes off Saturday morning.

 

So what was changed on the car between 4/28 when it ran great and 5/06 when it started surging again and the idle went high? Did you modify or change anything anywher either in/on the motor or in your tune?

 

Nope nothing, that's what has me puzzled. Sometimes it will stay running. Sometimes it won't. Sometimes it does it a little bit, sometimes it does it a lot and it will shut off and I'll refire and it'll shutoff. Etc.

 

im just wondering if a faulty map sensor could cause this problem, or maybe some sort of vacuum leak? ive got an 89 rs with a 350 and holley tbi unit. intermittently it will have a very erratic idle, and goes from almost stalling out to about 2000 rpm and back and forth. it sounds similar to what u are experiencing. i tried 3 diff chips and they didnt affect the idle problem. it seems to run ok once i get going, but it seems to be searching for an idle speed.

 

My map sensor was changed as well. When my idle goes crazy, my IAC opens and becomes very rich and very lean(enough to backfire). Could be a vacuum leak but my vacuum test on the engine says that I don't seem to have one.

 

Backfiring thru the exhaust?

 

Yep

 

Did you closely examine the gear on the dissy when you removed it?

I had a similar problem and it was worn dissy and cam gear.

 

Yea....I did. Looked brand new really.

 

i played with my car today. my idle is all over the place when it starts. it runs great once u get moving. i fixed a vacuum leak at the pcv valve and put a new throttle body gasket on because it was cracked. found the leaks with some good old carb cleaner. car is still searching for an idle though. i have a tbi chip. com chip in it. i have 3 other chips also, one hypertech and 2 more tbi chip.com chips. i threw in the other tbichip. com chip and the idle was worse, and almost stalled. i then put the hypertech chip in and the idle was perfect. only prob. with hypertech chip is that when i rev it up, the rpms dont come down fast enough, almost as if too lean. i ended up putting one of the tbichip. com chips back in. the idle is pretty much ok after it warms. but when it is first started or shut off then started, its pretty squirrely. try backing up while the rpm's go from 500 to 2000 and all in b/w. first it wants to stall then is chirps the tires,lol. im pretty sure my problem is with the chip.

 

Well, you problems is different from mine it sounds. My problem is only on cold start up of the day while its still in open loop but going towards closed loop. I let it cool for about 7 hours yesterday after the initial startup and got it nice and hot and it didn't do it. So, sounds like I might have a couple of collased lifters causing it to start and run ok then they pump up and all of that fuel that was sitting on top of the valves right there goes in and causings that rich smell and the engine is fighting to stay alive and not die.