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Tech / General EngineIs your car making a strange sound or won't start? Thinking of adding power with a new combination? Need other technical information or engine specific advice? Don't see another board for your problem? Post it here!
Voltage drop test looks a lot better with my regular DMM.
DMM reading 20.8 mV on ECM ground A12 versus scope showed 1.49 Volts. Ground D1 reading 23 mV on DMM versus 760mv on scope. Ground D6 reading 1.2 to 2.6 mV moving around a lot versus 1.14 Volts on scope. Ground D7 reading .1 to 3.3 mV moving around a lot versus 1.21 mV on scope.
There was no direct connection from alternator to the c500 connector so I added one and now getting 13.5 volts to Computer per TunerPro data. Feels better the more I drive it but still not 100%
i wanted to record in Tuner Pro but I get an error when selecting record that states could not create temporary log file. Tried rebooting but still get this error. Also when first booting program I get a settings error
Make sure the folder location for logs is set correctly and that the folder isn't read-only.
The folder was set to read only, worked before but Bit Defender was installed since the last time I data logged so it must have changed this setting. Will try tonight when I get home.
Here is a run with more voltage and I increased the injector size to 23lb to lean it out and ran the wide band in bank 1 at WOT was still rich at 11.2. Feels better at WOT but weaker at part throttle now also a lot cooler out in the 40's here.
I do get a puff of blue oil smoke on most hot restarts but nothing while running. I was going to change out the valve seals tonight but I have to drop the engine to be able to even remove the valve covers. I would go ahead and do this but am going on a fall cruise on Friday so I will wait until after this weekend. I am thinking maybe oil in the combustion chamber is my issue, either way they need to be changed and if this does not correct the start up oil smoke then it is a valve guide issue. The heads were gone through and all checked out and never ran this is why I did not even change the seals but they may have sat long enough to dry out the seals.
Meantime.... Now that your voltage issue appears to be fixed, we can start looking at the tune...
Looks like your VE tables could use a little work... BLM history is below. Picture 1.
I'd try to get your VE tables corrected before delving into WOT AFR's. However, before doing that....
One trick I used to get the non-WOT acceleration to be A LOT stronger was to play around with the O2 threshold tables. For whatever reason, GM had them such that the O2 threshold tended leaner at higher load. Maybe it was for emissions purposes... but it seemed bass-ackward to me. The LT1's using the DA3 code had the values increasing with higher airflow (as would be expected).
The tables I'm referring to are in the next set of photos. AUJP is the first trio and my current tables are the 2nd trio. You can see how biased my values are toward the rich side. What this does is allow me to get AFR's between 13:1 and 13.5:1 during moderate acceleration (still in closed loop, non-PE) rather than have the ECM fighting me to get back to 14.7:1 (sometimes even getting me into the 15:1 range). I noticed a major improvement in part throttle torque after doing this.
Since your BLMs are already well below 128, this mod will have the effect of raising your BLMs (ECM will want more fuel to satisfy the richer O2 thresholds, thereby raising the BLMs due to having to trim the fuel richer). After seeing the results of that, then you can tailor the VE tables to get the BLMs inline.
Looking at these tables they are similar to the AUJP except for the Fast O2 Threshhold shows .50 Volts across all Kpa. Looking at your O2 tables all voltages are higher however you have a MiniRam and I have stock TPI I am thinking maybe I will try to smooth it out in between to start with.
The only difference on this engine with the original tune is the heads were a 14102187 crappy swirl port design from what I have researched to the 14101081 casting so maybe this is enough of a change to need to tune here. Just strange that it did run pretty strong for maybe two tanks of fuel which is only about 10 gallons each.
Any rate, my modification is not necessarily Miniram-based per se. It's my overall combo. You'll have to iterate your way to the right tables using your WB (which is basically what I did).
BTW, I strongly advise getting your WB hooked up to TP. It's one thing to glance at your WB gauge while driving... it's quite another to be able to look at the WB data in detail vs the other things going on - delta TPS, MAP, PE vs non-PE, MAT, etc...
Me before WB hooked up to Tunerpro using S_AUJP => Screwing around aimlessly in the dark, going around in circles chasing my tail
Me after WB hooked up to Tunerpro using S_AUJP => Tuning
Kinda wish I could run Tuner pro. I have Accel DFI gen 6. It works great but the old software is DOS based and the ECM is not wideband compatible. I have an Innovative LC1 wideband installed but like ULTM8Z says, it makes tuning a PITA. I'll be swapping in my custom XT intake next summer with new injectors and I'll need to redo the fuel map, pretty much from scratch. I may try to connect an Innovative LM2 that will allow more data logging. I'll have to tap into the TPS and MAP sensor circuits to pick up that data. It should work though.
I am borrowing this LM2 from a friend and it is barely used and it is a PITA to work with. I have to reset it a lot to get it to warm up enough and start reading actual AF values. Take it apart and calibrate in free air and it helps but it is time consuming with all the power cycling to get it going. Not sure if this one is just a lemon or what.
Thinking I may just get my own and open to recommendations if anyone has any.
IIRC, ECM will add timing to whatever you tell it is the base timing is, in order to arrive at the value programmed into the spark map (plus whatever PE spark is called out, if any).
IIRC, ECM will add timing to whatever you tell it is the base timing is, in order to arrive at the value programmed into the spark map (plus whatever PE spark is called out, if any).
So it is what is being applied but may not be what is the actual live spark advance based off the ICM and/or distributor pickup. This is how I always interpreted without a crank/cam type sensor not sure that it could see actual real time values.
So it is what is being applied but may not be what is the actual live spark advance based off the ICM and/or distributor pickup. This is how I always interpreted without a crank/cam type sensor not sure that it could see actual real time values.
yeah spark timing isn't closed loop like fuel is. you tell the ECM what you're running for base timing and itll do the calculations and deliver a ref pulse to get the programmed value for the operating condition.
if your distributor is 10 deg more than what you tell the ECM you have for base timing, you'll get 10 deg more spark advance everywhere and the ECM wont know (or even care! lol...)
I was advancing the distributor for testing and watching knock retard on scan tool and just advancing until I saw knock then backing off. Tonight I wanted to know where it is at and I was in the low 20 degree area with est disconnected so I dialed it back to 6 degrees advance and it is way worse for power. Now it could be my timing indicator is off as I had to change them due to the normal position not being readable so I feel I must be off with my relocation.
If my indicator is correct is there any other reason the engine would want a lot of advance?
To the point of spark knock, engines usually like more timing. In fact - right up to the point that the flame front tries to push on the piston prior to it reaching slightly after TDC - they LOVE timing. With the TPI the ECM is expecting the timing to be what it is programmed for. But as long as you don't get the timing advanced so far that it causes spark knock you are going to be just fine. More timing is always better (except for emissions) *for making power*, right up till you squirt the rod bearings out of it.
Setting the timing on the distributor is your base - the point from which all ECM adjustments are made. If that's 6 then you add 6 to ALL timing adjustments made in software. Likewise for 10 or 20. The number isn't so important as long as you understand that everything you do in software will move up or down accordingly when you twist the distributor. Anything between say 0 and 10 degrees should work fine for a base. As long as you can say you are in this ballpark *for sure*..... I would feel safe tuning from there. More accurate is better since you can compare to known factory timing maps. I would attempt to get a more accurate timing number personally.
Be sure to clear codes after timing adjust. Having the timing connector unplugged puts the system in default spark. EST may not be active until you clear codes. Be sure to follow the factory timing procedure carefully.
Reasons why your engine might want added advance include a stretched or jumped timing chain. The elastomer on the balancer may have slipped also. Use you timing light to verify advance on throttle snap with EST active. Should hit 43 degrees.
Be sure to clear codes after timing adjust. Having the timing connector unplugged puts the system in default spark. EST may not be active until you clear codes. Be sure to follow the factory timing procedure carefully.
Reasons why your engine might want added advance include a stretched or jumped timing chain. The elastomer on the balancer may have slipped also. Use you timing light to verify advance on throttle snap with EST active. Should hit 43 degrees.
Excellent points here - sloppy timing chains and trashed balancer rubber are important to check for. I know mine were garbage after 30 years and 160k.
I just thought it was odd that I was over 20 degrees base and it ran decent at part throttle, which would put me at over 40 degrees at WOT, then backing it down to 6 it ran horrible (idles fine) and I can barley give it any throttle. When I first got it back together and running it was the same issue and since it was not backfiring through intake or exhaust I advanced the timing watched for knock retard then backed it off slightly and it ran great for a while.
The timing chain appeared to be OK, and no issues before the head and head gasket change. The balancer is new as the old one someone machined out too far and came off with no effort with the bolt removed so I put a new one on.
I will triple check my TDC marks as this seems odd. And I am looking for anything odd here as this is kicking my butt!
Is it possible you installed a truck balancer? Most of the truck V8s had TDC at 12 oclock.
Also, looking at your timing map, assuming 100 is full MAP value(100KPa), that is not enough spark rise at full throttle. You should have 29 degrees at 2,900 rpm. Most GM vehicles also had some advance at idle, beyond the 6 degree base. Many of the GMs I've checked idled around 20-22 degrees. Think of it as having manifold vacuum connected to vac advance. Advance should then rise as quickly as compression will allow, up to the 29 at 2,900 rule. The 29 at 2,900 rule is based on the rate of flame front propagation for gasoline at full enrichment/full throttle(high mixture density). From 2,900, advance should rise in pace with engine speed up to about 36 degrees at 5,000rpm. Some motors are happier at 34. You can play with this a little to find what works best.
As RPM increases beyond max VE(volumetric efficiency), MAP decreases. Therefore, the timing curve will move away from 100 MAP. As cylinder pressure and mixture density decrease past max VE, the engine will want more timing. That's where vacuum advance would come in on a conventional ignition. On EST systems we want to to program this in. I say 43 degrees but I've seen some peak as high as 48 degrees at light load. This added timing increases engine efficiency and helps keep things cool. The lower left corner of your map, max rpm minimum load, should be at 43-48 degrees and work its way down as MAP increases, rpm decreases.
Get that full throttle timing curve more aggressive and you'll probably find the power your missing. Set the dist to get base to match you map, then use the map to set your curve.
Not sure on the BCC below are pictures of what came with the car. The original tag is not o the chip and I could not find the BCC anywhere in TP should it be there somewhere?
Not sure on the BCC below are pictures of what came with the car. The original tag is not o the chip and I could not find the BCC anywhere in TP should it be there somewhere?
The bcc is long gone. Someone soldered in what looks like a dip. The knock board is from a 305 but will still work decent on a 350. Just wonder what the rest of the time looks like if the sa is screwy.
Few things I'm noticing... Doesn't look like any of them are a smoking gun though...
1.) You're stuck in BLM Cell 4. Go to the constant "Force BLM Idle Cell If CCP DC <=" and set that equal to 0. That'll cure that problem.
2.) You have a persistent code 42. EST Monitor Failure. Though not sure if that's just an artifact of when you disconnected the EST connector to check the timing.
3.) Your MAT sensor is showing awfully high temperature... up to 61°C. What does your air intake set up look like? Is the MAT sensor still in the plenum? ECM is going to seriously lean out the fuel mixture based on that temperature. Maybe you've compensated for it already with the WB O2... MAybe that temperature is typical for TPI with plenum MAT sensor... I guess I"m used to being a couple of deg over ambient with my cold air tube and relocated MAT.
4.) You're getting knock retard kicking in after you shut the engine off for some reason, but none while the engine is running. Strange... Though spot checking the reported spark advance (particularly at high load), it appears the ECM is putting in the spark advance that you're telling it to. Now, whether or not that's what you're actually getting seems like it's a question mark based on your observations.
5.) You never go into PE mode with this run. S_AUJP will report out when in PE mode and you do have that switch activated. Your bin says you're supposed to get into PE mode when MAP >50kPa and TPS >60%. You never hit those thresholds simultaneously, so it appears the reporting is accurate there....
5.) BLMs look ok. Some areas could use a little work... seeing some cells into the low 140's. The high load areas (for what cells you hit) are high 120's to low 130's.
It'd be good if you could the the WB hooked up so we can analyze AFR's.
For what it's worth, my car does the same thing- sort of. I'll tell my story here hoping to help you and me out.
On the stock 89 LB9 Auto map, APYY, my car used to run great, then one day it went flat at anything deeper than 3/4 throttle and above 4,000 rpm. Then engine would just fall flat and not climb in RPM or accelerate. It is 100% repeatable. If I use a stock 87 auto LB9 map, it does not do it. It does not matter which ECM I use (I have two). I'm not sure exactly when it started but since I've had the car, everything "bolt on" has been changed including the injectors, valve stem seals and timing chain. The car runs super smooth and feels brand new with the stock 89 APYY map, but it also goes flat as described. The car runs well, but not as smoothly with the stock 87 map. Again, this condition just appeared one day after I did a seafoam and I changed the injectors. FWIW, I changed the injectors back to the OEM ones and new problem was still there. I've had someone comment that it looks like it's going lean at the high rpms. I have not monkeyed with my adjustable FPR to try to give it more fuel but I will some day.
When I bought my 89 LB9 it was pretty much stock with 117,00 miles on mostly the original stuff. It drove well but needed maintenance and some repair so I started out by doing only what was necessary to get everything working/refreshed.
I think the car had not been driven hard for a long time and after more than a few of my blasts, long story short, my base timing was floating all over the place. I replaced everything in the distributor and ignition and still floated. I then changed the timing chain and damper and the timing chain was it. It had become super slack and the cam was floating back and forth on the slack and valve springs at idle. Once I did that, the base timing was solid again.
One thing that I have noticed is that day or night when I turn on the turn signals, the oil pressure needle swings up and down with the blinkers. This tells me my instrument cluster probably has a poor ground.
Your ECM ground check has me wondering if I disturbed something in one of the many jobs I've done on the car. If I understand correctly, these cars use an absolute reference to ground. If the ECM ground(s) is(are) poor, then everything will be off.
This is a particularly good thread IMHO. I will keep following and offer any help I can....
As far as the distributor tooth, if your base timing is set, it's set. If its off a tooth, your distributor might be rotated a bit more, but the timing is fine.
Last edited by Tootie Pang; 10-11-2018 at 05:08 PM.
The tooth off thing does not matter it was just a thought as I am running out of things to check/test. If I can time it where it needs to be and it runs well this is not the issue my distributor may just look more twisted to get it to the timing required but that is all this would cause.
So I guess the next question is why do I need to run so much base timing to get it to run decent enough to drive? I put about 400 miles on it last weekend and other then low power in PE it ran great and I can accelerate pretty good at part throttle, in fact this was a fall run and someone following me stated that thing takes off pretty good.
I suppose I could check the timing with a different timing light, mine is a Craftsman from the early 90's and I was burnt earlier in this thread with an out of calibration lab scope in DMM mode.
I decided instead of messing with verifying TDC to just advance for the best vacuum then retard a bit. This twisted the distributor a lot! Maybe I am off a tooth if I care to make the cap more straight on as it was before. See before post of the picture of the distributor orientation and now the after:
Now I can finally get to start fine tuning!
Thanks for everyone for the help with this, I am very grateful!
Few things I'm noticing... Doesn't look like any of them are a smoking gun though...
1.) You're stuck in BLM Cell 4. Go to the constant "Force BLM Idle Cell If CCP DC <=" and set that equal to 0. That'll cure that problem.
2.) You have a persistent code 42. EST Monitor Failure. Though not sure if that's just an artifact of when you disconnected the EST connector to check the timing.
3.) Your MAT sensor is showing awfully high temperature... up to 61°C. What does your air intake set up look like? Is the MAT sensor still in the plenum? ECM is going to seriously lean out the fuel mixture based on that temperature. Maybe you've compensated for it already with the WB O2... MAybe that temperature is typical for TPI with plenum MAT sensor... I guess I"m used to being a couple of deg over ambient with my cold air tube and relocated MAT.
4.) You're getting knock retard kicking in after you shut the engine off for some reason, but none while the engine is running. Strange... Though spot checking the reported spark advance (particularly at high load), it appears the ECM is putting in the spark advance that you're telling it to. Now, whether or not that's what you're actually getting seems like it's a question mark based on your observations.
5.) You never go into PE mode with this run. S_AUJP will report out when in PE mode and you do have that switch activated. Your bin says you're supposed to get into PE mode when MAP >50kPa and TPS >60%. You never hit those thresholds simultaneously, so it appears the reporting is accurate there....
5.) BLMs look ok. Some areas could use a little work... seeing some cells into the low 140's. The high load areas (for what cells you hit) are high 120's to low 130's.
It'd be good if you could the the WB hooked up so we can analyze AFR's.
just curious, I haven’t looked at the logs but is he running a Vss ?
The lack of Vss or like you were saying ccp sticks the ecm in cell 4 .
I decided instead of messing with verifying TDC to just advance for the best vacuum then retard a bit. This twisted the distributor a lot! Maybe I am off a tooth if I care to make the cap more straight on as it was before. See before post of the picture of the distributor orientation and now the after:
Now I can finally get to start fine tuning!
Thanks for everyone for the help with this, I am very grateful!
When you mean its back, you mean the engine runs fine? That is a pretty good amount of base advance. How do you set it? I would like to try that with mine.
Last edited by Tootie Pang; 10-11-2018 at 08:50 PM.
When you mean its back, you mean the engine runs fine? That is a pretty good amount of base advance. How do you set it? I would like to try that with mine.
Yes I have my power back under more than 40% throttle.
Setting this way I used a vacuum gauge connected direct to intake vacuum, then advance timingby twisting the distributor counter clockwise and watch the vacuum and stop at the maximum value then back off a little. Be sure to have EST wire disconnected while doing this, then clear the code 42 you should get from running with EST disconnected. You will want to have a scan tool to watch for knock afterwards.
09-24-2018, 08:38 PM
