RBob

iTrader: (1)

Check the negative battery cable between the battery and block. Can use the voltmeter and measure the voltage between the negative terminal of the battery, and a location on the engine block.

Do this with the engine running. The measured voltage should be low, less then .2 volts.

Can do the same between the positive battery terminal and the stud on the alternator. And between the positive battery terminal and other 'hot' locations. Again, looking for a minimal voltage drop.

With the engine running can also shake the harness and cables to see if that makes a change.

RBob.

88gunmetalgta

iTrader: (1)

Just checked those points. No voltage drop on ground cable. Maybe .13 from positive post to alternator. Nothing on the body grounds. Problem seems to have gone away for the time being though so that doesn't really tell me anything. I managed to get the ECM stuck in diag. mode and it wouldn't stop flashing code 12, pulled the ECM out, and when I plugged it in 20 min later I haven't had the problem since. I've been probing voltage and grounds from the back side of the connectors. Maybe it was just a bad connection at an ECM pin?

Cflick

That would bother me. A lot !
Unless I can point my finger at something and say with confidence "that was it" I'm not happy. How can you know that the "problem" won't rear its ugly head at the most inopportune moment ?

I'd take up RBob on his offer, and send it back.

dabomb6608

iTrader: (3)

What would cause my tune to run leaner when I restart on a warm motor, for instance if I drive and get it up to temp then go in somewhere to eat or to get something when I leave (10+ mins later) the car runs leaner especially at idle and very light throttle periods. I cant seem to find anything that is telling it to reduce fuel.

It seems to only do this till it gets back up to temp. It also seems like if I shut it off then instantly turn it back on that it isn't near as bad. Any thoughts?

RBob

iTrader: (1)

If the MAT is still in the plenum that will do it. Best to relocate it so that it reports true incoming air temperature and possibly switch to a bird cage style IAT.

RBob.

dabomb6608

iTrader: (3)

Im currently just running a filter on the end of my plenum since I still have my battery on the passenger side. Is there something in the tune I can change until I get a decent air intake on it with a relocated IAT? Is the IAT the same sensor as the MAT? The one underneath the plenum?

1991sleeper

iTrader: (-3)

Idk bout the other stuff .. But I know a cheap way to build a decent or better than aftermarket CAI .. Summit has 5' of aluminum tubing for around 30-35$ ..then all u need is rubber elbows or if u can weld aluminum u can make ur own elbows out of the same tubing ..

RBob

iTrader: (1)

You can change the CTS/IAT blend table to all 100%. That will take the MAT out of the fueling equation.

A MAT & IAT are similar, the difference is in the construction. A MAT is like the CTS, a solid brass bulb on the sensor end. While an IAT has an open bird-cage like structure on the end. This allows it to react faster to changes in temperature.

RBob.

ownor

iTrader: (5)

Wouldn't taking the MAT out of the fueling equation make it run lean or rich under certrain conditions?
On MAT/IAT, so the V6 MPFI style 'bird-cage' is an IAT and the TPI CTS-style is a MAT. But I guess the MAT is supposed to be mounted in the plenum whereas the IAT is really supposed to go somewhere near the air filter or something? I would think since relocating it from say the TPI plenum or TBI air cleaner to near the air filter would change fueling quite a bit considering the colder temperatures there.

RBob

iTrader: (1)

Yes, the fueling will not be as consistent.

A MAT reports intake Manifold Air temperature. An IAT reports Intake Air temperature. It is best to measure the air temperature in a location that best resembles the actual air intake temperature.

In one car I mounted the IAT behind the front grill.

RBob.

Ronny

iTrader: (1)

I thought there was a flag or two to uncheck?

88gunmetalgta

iTrader: (1)

Considering the frequency at which the problem was occurring, and the fact that it hasn't happened since saturday after I plugged the ECM back in, and how rare it is that an ECM itself actually goes bad, I'd say the problem should have shown back up by now if its gonna. Of course if it does happen again, its time for a closer look at the ECM than I can take.

bphage

Okay so I am a tuning NOOB converting my 88 IROC 305 to a 350 EBL P4. I was able to run a stock MAF tune - ran crappy - prior to conversion and not to bad on a stage 1 89 tune. I got everything for in for the EBL and set up two starting bins. My engine Specs are below and I figured they were similar enough to the vortec heads that I would use the Vortec VE and Spark table. Only thing I couldn't find was if darn EGR was NO or NC so I left it as it was in the stock tune.

Car fired up and it certainly felt to me like it was lean surging (rpms would increase quickly then drop then increase quickly then drop). It was only running for a few seconds before the SES came on so I shut her off to take a look at the code. I through a code 34. I tried to clear the code but couldn't figure out how... so I went ahead and tried to start the car up using the stock tune without the vortec head maps... car wouldn't start. Went back to the vortec tune and car started with SES on and was running way way rich so I shut it off now happy that the car would at least start.

I then looked to my WUD with engine off to figure out what was going on with the code 34 (see attached image) which didn't seem right. I checked the vacuum ports and they are all taped up really good so I don't think I have a vacuum leak that is causing the problem. I am slightly concerned about sharing vacuum with the FPR but others haven't had any problems. This is shared with all new 1/8 hard line and I bolted the MAP sensor in the factory location. I have read that some people recommend mounting the MAP sensor so that the vacuum port is facing down... I have it facing forward again this doesn't seem like this should be my problem. So this brings me back to the WUD that says its seeing 100kpa and ~13lb at boost with the engine off. I am thinking my new ebay 2 bar map sensor is not working right. Anything I am missing? I need to be able to idle the car long enough to do a VE learn so I am kinda stuck...

Engine Specs:

357 (350 40 over)
edelbrock performer rpm heads
edelbrock headers
1.6 Roller Rockers
crane cams 2031 lift at cam is 292/302 (=467/482 with 1.6 rockers) with 264/270 duration and 112 lob sep (new part number here: http://www.summitracing.com/parts/crn-104225)
2 bar GM map sensor
22 lb injectors @ 48 PSI

RBob

iTrader: (1)

Most definitely not a 2-bar MAP sensor. Or it is bad. At key-on, engine-off the MAP should be the same as barometric pressure, which at sea-level is about 104 KPa (it varies).

A code 34 is MAP low, sure it wasn't a code 33, which is MAP high. That one I would expect.

Need to fix the MAP issue first, then try starting and tuning.

A few months ago another EBL user got a 3-bar MAP off eBay. It most certainly wasn't... You can use the Diagnostic display to get the actual sensor values.

RBob.

bphage

Here is what I have on the Diagnostic display. The zero volts reading at 8 kpa seems about right for a two bar map sensor from looking at this site: http://www.robietherobot.com/storm/mapsensor.htm

I double checked the code 34 map low; and all three boxes are shown for that code. I can't get the car to start now but when cranking it only shows like 10 kpa... this still seems all wrong to me.

bphage

Okay well using this: http://www.chevythunder.com/map_code_34.htm

I figured out that my green didn't have the 5 volts it should have, turned out the wire was not connected properly in the wiring pug that came with the sensor, quick fix and voltage now makes more sense. On to struggling with tuning.

alex91z28

ok, my car running closed loop, steady throttle and speed, o2 sensor swings to much to the lean side, enough to notice a little skip or miss. what parameter can I change so this wont happen. I have 42lbs injectors.

RBob

iTrader: (1)

I don't believe that 87 KPa is correct. At key-on, engine-off, in Denver, a mile up (5200 ft), barometric is about 84 KPa. Indianapolis is not nearly that elevation (500 ft max).

RBob.

RBob

iTrader: (1)

Has the proportional gains been reduced? With larger injectors versus displacement this needs to be done. Same with AE PW tables.

RBob.

alex91z28

should I reduce it by half ,since im using almost twice has much injector.

RBob

iTrader: (1)

Yes, those and the AE PW tables.

RBob.

Cflick

I'm finding an elevation for Indy about 700 feet.
My house is 1004 feet, more or less, and key on engine off MAP is typically 97 kPa.
( also 97 at 4400 RPM and WOT, so I think I'm flowing air OK )

I'd guess Indy should be 97 or 98 kPa key on engine off, typically.

bphage

You guys are right; I went and bought a new sensor and it now reads at 100 kPa. Matches the stock one in my supercharged Bonneville when I threw a code reader on it.

Thanks for the heads up!

I have been working on the VE learn in park running through the RPM range slowly (upto 3K rpm) and it is running much better. I don't understand how it idles well when warm in open loop but still won't hold idle once it goes into closed loop. I took it for a small drive in VE learn around the block at like 5 mph and it made a few more corrections.

I am trying to go slowly as I don't want to ruin my new engine. Heck... I am still tightening the header bolts with heat cycling so I know I have exhaust leaks which then go away after i tighten it... I hope this goes away with several more heat cycles. Here is the VE curve that is developing; does this seem reasonable so far? Also I don't understand the effects of an exhaust leak in the VE table anything I need to look for?

Thanks guys... back to reading these posts so I know what to do next

alex91z28

ok ,prp gain vs o2 error,prp gain multiplier vs airflow,prp duration vs o2 error,prp duration offset vs airflow and ae map pw,ae tps pw ,all multiplied by .5 drove the car and it feels much smoother.
is it ok to change all of this prp tables.

RBob

iTrader: (1)

With that cam the idle should be fine. May need to reduce the idle SA compensation and/or reduce the proportional gains.

An exhaust leak will cause the ECM to add fuel, as the O2 sensor will be reporting lean. Not sure about the 25 KPa column of the VE table. Not sure as I'm not sure if that area was hit in the VE Learn, it is higher then the 20 & 30 KPa columns.

RBob.

RBob

iTrader: (1)

That is OK. more so since it did the trick. Got rid of that bad U-joint sound?

RBob.

bphage

You guys are good.... I the 25 kpa column was barely hit as a recal like one or two cells, I have manually lowered those columns and I am going to see what happens today. The VE learns have been taking away fuel so I don't think I have hit the limit of the exhaust leak yet... but working on fixing it all together.

Sigh... I swear I am searching but I just don't see an answer to this... when I took the IROC around I noticed the MPH wasn't showing on the EBL. Vader Had a nice post as to the importance of the VSS signal Here: https://www.thirdgen.org/forums/tpi/...terrelate.html

So I need to trouble shoot the VSS signal - I know the wire is in the right place from the conversion, I have the correct gears in the transmission and I have a mechanical cable that goes to the speedo so I believe the VSS is behind the gauges... I know its not on the transmission. I have a b&m shifter with the park/neutral safety switch always on so it would be possible to start in any gear, but I don't think this would interfere with the VSS. Is it possible there is a setting somewhere that I missed on the EBL for the VSS signal? Also, can I continue to tune with the EBL without the VSS signal or must I fix that first?

RBob

iTrader: (1)

Need to un-check the MagVs option flag:

Option Word 3 - Bit 4 - MagVs

Also change the VSS PPM to 2002:

VSS - Pulse Per Mile

The included calibrations are set up for a magnetic VSS and 4K PPM. That is for the '90 - '92 TPI cars.

RBob.

bphage

Fixed it! whoo hooo!

alex91z28

here is a log of my car at idle. blms are 128 steady and sa are 19 to 20, but idle speed goes up and down. cant figure this out.

mine u joints are still holding! so far.

RBob

iTrader: (1)

Went too far in reducing the proportional gains. Note in the log how the INT is moving up & down to create cross counts. This is causing the slow rise & fall in the idle RPM. Even the IAC gets in on the act making it worse.

If the car doesn't need to pass an idle sniffer test the easiest fix is to set it for open loop idle. Set this flag:

Option Word 1 - Bit 2 - OpIdl

Otherwise, work with this parameter:

PRP - Prop Gain Offset for Idle

Increase a bit at a time until the INT and idle settles down. Need enough prop gain to keep the ECM happy with a steady INT. If the starts to rise & fall quickly then there is too much prop gain.

RBob.

bphage

Okay guys I could use a little help here. I Started with the VE log that I manually adjusted and I have spent the rest of this time trying to get first gear VE learns on flat ground and during idle. This was the resulting VE table "last VE learn."

Long story short with the MAF the car idled in the 600 rpm range, I am unsure if the VE table is lean enough in the lower RPMs to allow for the correct idle?

Here is what I have tried. I changed the high and low compensation tables. I increased upto 3 deg and resulted in a worse idle, decreased it down as far as 1 deg and still made it worse so I reset it to default.

I then repeated the above using the aluminum head spark table, I have been using the stock table so far. The results were the same.

I have not yet tried the proportional gains mostly because I don't understand it yet and have been trying to find existing posts on it before trying but it is now next on the list of things to try.

It seemed that under the current settings it would like a higher idle. So I added 225 rpm to the in gear and park tables and the car now idles in the high 700s to low 800rpm range. So now if I start cold and let it warm up the car idles rock solid but once it gets over 80deg or so it starts to have trouble I would describe it as a rolling idle.

So I have two problems, one it seems my idle is way to high and I am not sure what to do to get it lower other than starting to play with the proportional gains which I don't yet understand. I feel that my VE table in the idle range might be contributing but don't have the experience to know.

The second is now that have increased the idle it warms up and I get this unstable idle that is very similar but not as pronounced as it is when I had my idle set lower. I think they are linked but again don't understand how.

I have attached the warm idle data file if anyone would take a look at it.

Thanks in advance.

bphage

Okay I played with the proportional gains here is what I found... I just don't understand it.

Using the bin that would have a 'rolling idle' when warm I decreased the PRP - Prop Gain offset for idle from 2 to 1. It wouldn't seem to let me do less. This resulted in the car stalling out at idle. so I reset it back to 2.

I then decreased the PRP - Prop Gain Duration for idle from 32 to 25; i wan't sure if it made a change but it seem mildly better so I changed it from 25 to 15. The open loop fueling didn't seem to like it all that much but it quickly went into closed loop where it did seem to make an improvement. I have attached that data log.

I then went to the original idle table (i.e. I removed the extra 225 rpm I added) and decreased the prop gain to 15... remarkably the car didn't stall out, although it still seems to have a rolling idle. I have also attached that data log.

If anyone would be willing to take a look that would be great.

Thanks.

Cflick

Briefly, ( and incomplete, but should get you in the right direction )

When the O2 sensor says "lean" the ECM responds by adding fuel.
Without getting too involved here ( you'll catch on ) if it's only a little lean, the ECM only adds a little fuel. If the O2 says a lot lean, the ECM adds more fuel.
If the prop gain settings are off, the ECM either adds too much, and goes into a loop fighting itself ( rolling or surging ) or doesn't add enough, and it falters.
Call it overshoot or undershoot, with the complication that undershoot can cause it to go into overshoot.
I found it easiest to lock down spark, so I know that isn't adding complications, and work on the prop gains alone until it got smooth enough for me.
I also disabled stall saver ( by setting the RPM way low ) and let it stall while working on that, again to eliminate additional confusion on my part.

Keep in mind that the prop gains work off of the INT, not the BLM. Prop gain and INT are fast. Faster than the VE table, which is BLM.
If VE is right, but prop gain is off, you'll have an unstable idle, but on average, the AFR will still be very close. That's a hint.

RBob

iTrader: (1)

Looks like too much smoothing on the VE Learn. Note how the shape of the VE graph went flat, it lost the natural curve of the VE Learn even where learning did not take place. Also, do not use Tuner Pro's smoothing.

RBob.

RBob

iTrader: (1)

Proportional gains are what Cowboy posted. In closed loop the ECM uses them to force the AFR to oscillate. So that the AFR basically averages stoich.

The IAC counts are too high, need to open the throttle blades to get them in the 20 - 30 range on a warm idle, no other loads. Don't worry about the TPS voltage unless it goes over .75 volts or so.

Change this value to 25.5:

IAC - Volt Drop for Steps

This will prevent the IAC from bumping the idle due to the fluctuating system voltage. Which also needs to be looked at. At idle the IGN+ voltage is low, it varies between 11.9 and 13.0 volts.

The fuel pump voltage is even lower at 11.0 to 11.5 volts. The oil pressure switch and/or fuel pump relay may be bad.

Before I forget, set this value to 1100 RPM:

BLM - Idle Cell RPM Threshold

That will prevent the BLM from getting reset each time the idle RPM goes to 800.

The O2 sensor signal is totally foobar. Not sure what to think of it, although the engine does respond (it surges) when it shows the AFR going toward the lean side. But the signal is all wrong.

Double check that the O2 ground wire is good, ECM pin E15 to the engine block (TAN).

And the signal wire from E14 to the sensor (PPL). It also may be that the sensor is bad.

Can't really do more tuning until there is a good O2 signal and the system voltage is steadier.

RBob.

bphage

Thanks for the very practical explanation, this helped a whole lot!

bphage

Thanks, I thought that was the case. I used tuner pro's smoothing to get the pre-VE learn curve. After that its been nothing but VE learns. I didn't want to really think about smoothing factors so I left it as default; I will need to go back and change that as its clear I have a few other things to work out.

bphage

Thanks, once I had some more understanding it helped me to put things into perspective. I think I can play with this value some more to get things working better.

Thanks, I was starting to draw the same conclusion with the IAC counts but couldn't see a link between the idle and specifically the sinusoidal idle I was seeing. My TPS voltage is .6 closed and over 4 volts at WOT but only shows 95% on the WUD for some reason... from some of the other posts it looked like adjusting the blades would be helpful but again when I graphed the values in excel and ran a correlation analysis I couldn't find anything that seemed to match the sinusoidal pattern. This made me hesitant to change it before I understood the sinusoidal nature of the idle.

Done and Done. Ah the electrical system. So I have the march aluminum under drive pulley set. Long story short with the pulley set it won't start charging until over 800 rpm or so which is why you see 12 volts roughly below 800 rpm then upto 13v roughly above 800 rpm. I was concerned that this would create an injector pulse width issue but two EE friends of mine thought it wouldn't be a problem. With my intended use of the car there should be no problem charging the battery as I won't idle long enough to need to worry about it not charging while at idle. If I could keep the RPM stable I wouldn't see the voltage changing all over the place. I looked at the voltage change and it didn't seem to correlate to the sinusoidal idle so I wrote it of as an unlikely cause. But, changing the steps to ignore this would probably be a good thing. So I will make that change. I would consider using a bigger alt pulley but I can't seem to find a nice aluminum one to match the rest of my engine... so I was "living with it."

The fuel pump wiring does have some resistance to it... I now forget what wiring diameter GM used but if you ever measure the resistance it drops like 1-.5 volts or so from the relay to the pump. I was thinking of running a new larger wire to deal with the aeromotive stealth 340's higher amp draw, but given the short distance of the wire and amperage it was more than sufficient even though the resistance was less than ideal. Also by the time this becomes a restriction on the fuel pump I know I will be adding an external fuel pump so it was a bit of a mute point at the time. The Fuel pressure at the rail is stable despite this voltage change. I know the relay is okay, I don't remember if I checked the oil pressure switch, but my oil sending unit is FUBAR too so I will probably just replace both when I go to put in larger injectors for the turbo this summer.


That makes sense, I didn't catch that at all... thank you.

I knew the there was something I was missing with the sinusoidal looking idle... if the o2 sensor is FUBAR then it would be the cause of the idle that I am seeing. I don't understand why it kicks in when at operating temp more than when cold or how its masked with a higher rpm. I have edelbrock ceramic coated tes headers and they have a new o2 sensor in them from edelbrock. As I recall it had to be there o2 sensor because a stock sensor would not work correctly in there headers. I also need to install the wide band o2 bung in the Y pipe... so I think I will be taking everything a part and looking for issues you mentioned + anything I missed.

Thanks so much guys - I attached the idle I was seeing just in case someone else runs into this crazy problem.

RBob

iTrader: (1)

A smaller alternator pulley will spin it faster.

RBob.

mhelander

As inspected the van, tailpipe smoke sniffer was indicating different excess O2 figures per tailpipe. Most likely cause is leaking intake or throttle body gaskets or other quite serious vacuum leak.

As there was serious hissing sound in passenger side of throttle body bought some weeks ago new TBI gasket and PCV. Yesterday got those installed and stock gasket had completely collapsed in area of IAT passages and ported vacuum labyrinth.

Now I got idle back...

And, with little EBL self-learning using NB it now goes HWY speeds 8-11 km per liter which is 13-15 liter per 100 km. Not bad at all for FlexFuel as it consumed about same amount of 95E with stock cam.

Doober

Need a refresher... attempting to pass emissions, and I don't remember what I need to do O2-wise. The headers have a stock location for a non heated sensor, and a location near the converter that I use for the wideband sensor. Will it freak out if I put the n/b in the stock location and unplug the w/b? I'm not 100% sure the w/b is functioning correctly. I believe the TBI may have the classic leak around the throttle blade shaft, have yet to verify that though.

morgsie

iTrader: (1)

Leave your WB where it is as long as it is PRE cat. Put a heated (3 or 4 wire) NB O2 in the headers. Or add another bung close to where the WB is, but that is more work. I have my WB in the passenger side header collector and the NB in the drivers side header collector. Seems to work fine, but I haven't gone closed loop yet. NB still reports on the WUD though. Why do you not think the WB is working correctly? Exhaust leaks will affect the WB. The throttle shaft will just cause poor/inconsistant running, not the WBs fault it's reporting rich or lean because the engine has a vacuum leak. If you have a BB TBI I was able to get a guy locally that rebuilds Holleys to bush it. The shafts are almost identical in diameter.

Doober

It passed emissions 2 years in a row as it sits. I've changed a couple tune things here & there but it was so long ago I don't remember what. The exhaust is a crossover type, where the w/b is. I'll be using either type of n/b, whatever was stock on the truck... only one I see listed is 1-wire, so it'll probably be one of those.

morgsie

iTrader: (1)

Get Acdelco p/n AFS74. Most electronics supply places have the 3 pin weather pack connectors.

Doober

Good to know except for the fact I'll be running the 1-wire like I originally posted, if that's what it had to begin with.

1991sleeper

iTrader: (-3)

Hey guys I'm in the process of rebuilding the little stock LO3 and my tune was 95% complete before I tore it apart .. AFR was within .5 all across the rpm and map range in open loop , never ran it in closed loop ... It already had 1.6 rockers , CFM tech TB , headers, and full 3" exhaust with a 3" cutout for the track ... I was running the stock injectors @ 16 psi ... And I will be using the 350 68# ? Injectors when I get it back together with a VRFPR .. And I was just wondering what I should do with the tune before initial firing of the engine ? ... It will be around 10-10.5:1 CR , .488 .495 cam lift with 270* dur advertised + the 1.6 rockers so .528 lift on exhaust , Summit stage 1 intake , ported LO3 heads , heads intake headers etc. all port matched and I think that's about it ... Thanks for any input !

morgsie

iTrader: (1)

Suit yourself. A heated O2 will go into closed loop a lot quicker and stay there. My car originally came with a 1 wire O2 and in cold weather, even after warm up it would cycle between closed and open loop. A heated (3-wire) O2 took care of that.

ownor

iTrader: (5)

this is gonna be an interesting build, decent CR and cam on LO3 heads? you prolly got that done already but just to make sure, imho the stock heads are just setup for like 450 lift or something.
bottom end is a rebuilt stocker with new pistons for that kind of CR?

Dominic Sorresso

Sleep,

I did a somewhat similar TBI motor a few years back w TFS23d heads,
a Comp Cams roller single pattern 269 duration, .528 lift w 1.6 roller rockers.
Overlap was 53d and 108d LSA. I used #80 BB injectors running 20psi at WOT,
10psi at idle. Injector DC was <80%. Used EBL BTW.