Just triple checked, and the TB blades look closed 100%, no thermometer, but I could buy one possibly if it'll help.

 

It's not a video. When you are done recording, click the stop button. Then on the bottom you'll see a save button, click that. It'll save as a MS excel file. Once saved, go to the file folder it was saved in and right click, select send to, and select zip. It'll save that file in zip format. Then come back here, click reply, go advanced button on the bottom, then the paper clip on top and attach the zip file to your post.

I know you just did a lot of maintenance and this condition followed that maintenance. So something you did caused it. Gotta retrace all the steps until you find it.

 

Thanks again. I got to be away until monday, I'll try to log that data and send it out then. How long do I need to record? From start to operating temps?

 

10-15 minutes worth from start up should be good.

 

I serious doubt this is going to work, I couldn't even see this on my own computer. But lets see, this is the file that appeared on my desktop after running this thing for 15 minutes or so. Fuel trims are all over the place once again. Hope it works. I hope the attachment is there. Sorry everyone this is very new to me.

 

This is the MALF file that Scan9495 uses to do the data logs. Your data log should say "DLOG-Save-(Insert Date Here)-(six digit number)-(insert VIN here).csv"

For Example, one of my Data Logs is saved as "DLOG-Save-2015Jun18-143024-2G1FP22P8S2198722.csv" Look for something like that. It usually saves to the same location that the MALF.csv file is located.

 

attempt 2, it saved as a media player file, I hope u can still extract the log somehow.

 

Please let me know if this works. If not I can try something else.

 

For some reason your datalog is showing a MAF reading. Not sure what effect that is having (I don't think it is effecting anything). Your MAP is 10-20kPa lower than most other stock LT1's, I find that odd. Your surge in idle is definitely caused by the IAC opening up, but I can't see why it's commanding more IAC for seemingly no reason. It only does it in closed loop, so it's related to O2's and the fuel trims coming off of them. The PCM is still adding fuel, but it's within the trim limits so it shouldn't be the cause of the issue. Then, for some reason, at the end of your log, it smoothed out, but it gives a wicked BLM split. 108 LTBLM and 102STBLM on the Left and 147LT BLM on the right. It's maxing out the Left bank to pull as much fuel as it can possibly pull.

I'm not so sure I'd trust this datalog. It's showing a lot of breaks in the data stream (the sudden jumps in RPM and skipping during play back). At the end of the log, did the idle smooth out like the data log shows? If so, that happened after a sudden and drastic change on the BLM's. If that's the case, I'd be wondering if the PCM was going out. Or some bad wiring (possibly a loose or corroded ground to the PCM).

Hopefully someone else can look it over too.

 

It does idle a bit better after a while, but the richness in the exhaust makes my eyes burn...set off the smoke alarms in my house even with the doors closed. Hope someone else can chime in with this. I'll look over the grounds, maybe clean them up a bit. As far as the computer being the issue, is it just the "blue chip" I'd need replaced, or the entire assembly? And where's the best place to score one? Junkyard? Ebay?

 

Where are you located? I wonder if the MAP is bad.

 

I'm in montana. Junkyards are very slim here. Map sensor us about the only sensor that isn't new, that and my ign module

 

Are you on a mountain? Like 6000+ feet?

 

Orreilys has the map sensors in stock, I'll just swing by and scoop one up. Cross fingers! Hate to spend yet more money, but if the readings seem off, I'll take your word. Could the pressures in the engine be what is causing odd readings on the sensor?

 

Your MAP looks low for Baro and idle. Unless your at high elevation, it doesn't make sense. But low MAP would give the computer "thin air", which should give you a lean condition, not rich.

 

Well damn....it's far from lean...I been reading that map sensors hardly ever go bad. Is it worth replacing?

 

The "O2" is showing lean....that is why the short terms rail at 160, then the long terms start to shift up, and if they compensate enough for the lean condition, the short terms will start oscillating lean, rich, lean, rich, which is normal for short terms. They should always be going lean, rich, lean, rich, etc.

The data shows where you have one O2 wired to both banks. Is this the case? Do you not have the O2 situation properly fixed yet? Interesting that the idle trouble seems to start when it goes into closed loop....as you go into closed loop, engine temp is rising....

I agree with HRC, the IAC appears to be directly causing the change in RPM. So the question is....Why is the PCM changing the IAC position?

According to the '93 service manual, IAC position is calculated based on battery voltage, coolant temp, engine load, and engine RPM.

In some of the idle troubleshooting charts, the PCV valve needs to be checked for proper operation along with the PNP(Park/Neutral Position) switch, is your car an automatic? As the thing seems to start acting up when going to closed loop, I don't think those things are bad...otherwise, I think it would be moving the idle around in open loop.

Going back to the IAC variables....RPM is one of them...and you keep getting a code 36. RPM is determined by the opti if I'm not mistaken. If it's dropping(or gaining) reference signals, then the PCM may think the RPM is falling and open up the IAC to try and counter act it....but why only in closed loop....heat related issue as the engine gets hot maybe...I'm not sure.

A code 36 means you are losing the high resolution signal or getting extra low resolution pulses according to the factory service manual. This code is set when the failure occurs 5 times in a row.

Did this idle problem develop before or after you installed the MSD opti?

Here is some reading for you....
https://www.mediafire.com/?40mfgeoe4ctti

Download the 93 factory service manual and start reading at page 6E3-A-1. That is the start of the LT1 troubleshooting section.

 

You got everything right. I do only have 1 o2, with a jumper going to both since this issue has started, and yes, problem have just heppened since a new msd option intalled. You knocked it out of the park and I respect your knowledge. So you feel my first step would be welding in a new o2 bung on the drivers side bank? And getting that put in?

 

I see the single O2 as a problem, but I'm not convinced that it's "the problem" as you mentioned that it's been running fine for three years with just one O2.

I've been looking at the low and high res data. The high res is consistent. The low res shows a couple of odd anomalies.....that does not correlate to the rpm logged at that time. I'm not sure if that is scan data issues or the problem that the PCM is flagging the code 36 for....

However as the PCM is flagging code 36, that is related to the signals coming from the opti.....so it's seeing something it does not like that the scan data is not showing. The scan data is only as small sample of what is really going on with the engine. To properly see what the opti high and low res signals are doing, we would need to put an oscilloscope on it.

Just to clarify, the engine was performing okay before your tune up correct? If so, I think something you changed is causing this issue....maybe the MSD opti or another of those components you changed.

 

Yes, it wasn't having any of these issues prior to the tune up. I replaced spark plugs, wires, opti, ign coil, water pump, water pump sensor, injectors, all vacuum lines. I've already took the opti off and inspected it closely, all seems just fine with it. Could bad plugs/wires cause it? A ground maybe? I'm really glad you guys are able to know what your looking for on that log. And yeah, the thing ran for years with just 1 O2 hooked up without anything wrong. The code 36 hasn't tripped the sel as of the last week or so.