Rough idle after 411 swap

[Tparkhill]

Hi guys. 97 Suburban with a 411 swap that has been nothing but problems. A few days ago I figured out that the EGR was stuck open so I disabled it in the tune and blocked it off by putting a piece of aluminum can between 2 gaskets and reinstalling the valve. But that changed nothing about the way it runs. I have a very rough idle that is proving to be incredibly annoying. I thought a crank relearn would do the trick but I think it just hid the misfires. The truck was misfiring on all cylinders before the relearn and somehow they magically went away after the relearn.... but it still felt the same... Ive checked all the wires at PCM countless times and everything is right. NOTHING was wrong with the suburban before this terrible idea of mine to swap a "better" PCM in. I'm not sure what to do next... please help


I'm going to attach a short log of idle as I suspect the O2 readings shouldn't be jumping around like they are.

[SultanHassanMasTuning]

do you have a wideband instaled, i wouldnt trust 20 year old narrow bands

OPEN LOOP IT AND GO OFF wideband

[Oleblu]

I had similar issues after 0411 swapping my 97 Silverado. Even if the egr is disabled in the tune it will still cause issues if left plugged in. Leave it unplugged in case you haven't already done so.

[Tparkhill]

I had similar issues after 0411 swapping my 97 Silverado. Even if the egr is disabled in the tune it will still cause issues if left plugged in. Leave it unplugged in case you haven't already done so.

Did you ever figure out the issue? The EGR is unplugged and blocked off.

[Oleblu]

After I unplugged mine my rough idle issue went away. How rough is it honestly. your making it seem very rough. I always noticed my idle was rough with both the black box and the 0411. I have since then ditched the factory intake and cam swapped mine. Its a whole different animal now. But Before the cam swap, once I got both my maf and ve within -5% using wideband in open loop the idle is much better. As sultan was saying.

[Hutchinson]

What Operating System are you using? And where did you get the initial base tune? Is it a 2002 Express or Savanna van tune (5.7L/4L60 or 80e/etc)?

I'm using the 12212156 OS, with a base tune from a 2002 Chevy Express Van (5.7L/4L60e/4WD) which has been modified to run my swapped 383 crate engine. There are several Express/Savanna stock tunes (like mentioned above) that you could use,... if needed. There were already a few 4L80e's in the repository, but no 4L60e's, so I put a couple 60's on there,...so that's covered.

For the EGR, I knew I wouldn't be installing it back on the new crate engine, so I bought a block off plate, and left the wires taped back up into the harness. After this, I did the crank relearn (which took a couple times), and rotated the dizzy to set timing within +/-2 degrees (that was easy). That's all I had to do. Are you throwing any DTC codes?

Outside the above, sounds like maybe a base tune or PCM issue (I know, I know,....duh). Maybe try downloading a stock base tune (as listed above) and see if that helps,....maybe your base tune could be corrupt??? I've previously experienced,......engine ran fine,.....I downloaded a new tune/didn't like it,....re-uploaded my original tune,....engine ran rough as gutts,....re-uploaded my original tune again and it ran smooth as butter like before. Don't know why,.....

The 0411 swap actually made my idle roughness smooth way out,....way better idle than the ol' black box. Once you get this idle thing behind you, I think you may like your 0411,....I know it's frustrating right now though.

[Tparkhill]

After I unplugged mine my rough idle issue went away. How rough is it honestly. your making it seem very rough. I always noticed my idle was rough with both the black box and the 0411. I have since then ditched the factory intake and cam swapped mine. Its a whole different animal now. But Before the cam swap, once I got both my maf and ve within -5% using wideband in open loop the idle is much better. As sultan was saying.

I think I'll try doing what you did with the VE and MAF. But could you explain exactly what VE is and what it does? And as for the Idle its seems fine except for ever few seconds I get a surging sensation that's enough to "vibrate" the passenger seat visibly

[Tparkhill]

What Operating System are you using? And where did you get the initial base tune? Is it a 2002 Express or Savanna van tune (5.7L/4L60 or 80e/etc)?

I'm using the 12212156 OS, with a base tune from a 2002 Chevy Express Van (5.7L/4L60e/4WD) which has been modified to run my swapped 383 crate engine. There are several Express/Savanna stock tunes (like mentioned above) that you could use,... if needed. There were already a few 4L80e's in the repository, but no 4L60e's, so I put a couple 60's on there,...so that's covered.

For the EGR, I knew I wouldn't be installing it back on the new crate engine, so I bought a block off plate, and left the wires taped back up into the harness. After this, I did the crank relearn (which took a couple times), and rotated the dizzy to set timing within +/-2 degrees (that was easy). That's all I had to do. Are you throwing any DTC codes?

Outside the above, sounds like maybe a base tune or PCM issue (I know, I know,....duh). Maybe try downloading a stock base tune (as listed above) and see if that helps,....maybe your base tune could be corrupt??? I've previously experienced,......engine ran fine,.....I downloaded a new tune/didn't like it,....re-uploaded my original tune,....engine ran rough as gutts,....re-uploaded my original tune again and it ran smooth as butter like before. Don't know why,.....

The 0411 swap actually made my idle roughness smooth way out,....way better idle than the ol' black box. Once you get this idle thing behind you, I think you may like your 0411,....I know it's frustrating right now though.

Hutchinson, thank you for the detailed message and taking the time to reply, every bit of help means a lot.

My Operating System looks to be 12208322 with what should be a stock 2002 express van tune that I got off the repository. (I have modified a few things like transmission and some codes) The PCM is out of a 2001 blazer. Now, I have a couple other 411's that I grabbed from the JY thinking I unlocked all blazers and Jimmy's but I found out that the 6 credits only lets you do unlimited of 1 year/make... so I cant just swap in one of my other without shelling out $100 to unlock it.

The interesting thing that confuses me is that I was getting a P0300 before the crank relearn (which it wasn't wrong the engine was definitely misfiring) and now it still misses but the PCM shows absolutely ZERO misfires...

Should I upload my tune for you to look at?

[Fast4.7]

Hi guys. 97 Suburban with a 411 swap that has been nothing but problems. A few days ago I figured out that the EGR was stuck open so I disabled it in the tune and blocked it off by putting a piece of aluminum can between 2 gaskets and reinstalling the valve. But that changed nothing about the way it runs. I have a very rough idle that is proving to be incredibly annoying. I thought a crank relearn would do the trick but I think it just hid the misfires. The truck was misfiring on all cylinders before the relearn and somehow they magically went away after the relearn.... but it still felt the same... Ive checked all the wires at PCM countless times and everything is right. NOTHING was wrong with the suburban before this terrible idea of mine to swap a "better" PCM in. I'm not sure what to do next... please help


I'm going to attach a short log of idle as I suspect the O2 readings shouldn't be jumping around like they are.

I would check your distributor drive gear for wear. Mine went bad on my 1997 Express in under 100K miles to the point it was misfiring and bucking at highway speeds.

As for the 0411 swap, I would recheck all your wiring. You could have something pinned wrong. If for example you had an injector pinned wrong or the 02 sensors swapped it would run terrible.

That being said my Express ran MUCH SMOOTHER with the 0411 stock tune than the tuned Black box. My Express van has had an idle shudder that feels like a misfire for as long as I can remember (My parents bought it in 1998 with like 11K on it). I actually got so tired of it shuddering with such a mild cam, that I threw a much larger cam in it, just so that I had an excuse in my mind for it to run that way!

[Hutchinson]

I'm not sure what the 12208322 OS is,....someone else will have to answer that one bud,.....if it's the right one for you to use. I'm presuming you have the 5.7L Vortec, 60/80e trans, in your 97 Suburban? Might be good if you put your vehicle description, engine, trans, mods, etc in your signature so people know whatcha got for all posts going forward.

I can only say what I used for the base tune in my 96 K1500/0411 swap,...and it works good (listed above in post #6). Did you use LexTech's Pinot sheet when you did the 0411 swap?

With your crank sensor not properly adjusted to the cam sensor and/or your PCM (thus reason you need to do the crank relearn), your pair if sensors (crank/cam) weren't "in tune" together/with the PCM thus, producing a misfire "reading". When you subsequently did your crank relearn, it tuned the cam/crank/PCM together (as they should be) and as a result, your "detected misfires" goes away. Mine did the exact same thing,.....I had a P0300 until I did the crank relearn, and they went away,...I now show zero misfires. Read up on Google how the crank/cam sensors detect misfires and you'll see what I mean.

As far as your surging issues that visibly shake the passenger seat,....man, that don't sound good,..especially since you state the truck ran perfect before the 0411 swap,...and all your pinouts are right. 9 times out of 10, it's a pinout wire in the wrong spot,....but, you've checked it,....I'd say, please check it again (for shits and giggles).

Post your tune and a scan at idle/driving so some of the more experienced guys in here can look at it,....

As for telling you what VE is,....man, that's a tough one to explain on a post,....your simply gonna have to read up on these things,...it's a lot to learn/put together in your mind

We're here to help bud,....no worries,...it'll get sorted.

[Hutchinson]

Hahaha,...that's a good fix Fast4.7,...bigger cam huh? That's genius.

[Hutchinson]

Tpark, I just got on my laptop and had a look at you scan file from first post. My 02(mv) jumps around like that too at idle,...but as soon as I increase rpm's it smooth's out to 100-900mv rhythmic cycle switching. Your O2bank 1 and bank 2 switching looks good, your LT and ST fuel trims look good (wish mine looked that good), your injector pulse width looks good. Only thing I see different,.. I'm running bout 21-22 degrees spark at idle, whereas, yours is saying 17 degrees. I don't know if that's an issue at idle or not,...maybe one of our more experienced guys can answer for you. Does your truck run good while driving,...only having the idle issue?

[Tparkhill]

Thanks for the help guys. I'm going to take a look at the timing, I never even noticed that. I downloaded your stock express van tune from the repository and its way different in every way from your bin.. I'm guessing the guy i bought it from doesn't have a clue what hes doing....

I have a few other OS's I can list if you would like to see them. I might also just spend the credits and license your stock file and just run that and cut my loses...

Hutch- The only time it runs rough is at idle, it drives GREAT on the road/hwy - no problems with power whatsoever

Here's a scan of it driving with a couple WOT pulls. its kinda lengthy but its what I have available right now.

first log with suburban.hpl

Sig updated

[Oleblu]

I think I'll try doing what you did with the VE and MAF. But could you explain exactly what VE is and what it does? And as for the Idle its seems fine except for ever few seconds I get a surging sensation that's enough to "vibrate" the passenger seat visibly

Maf (Mass air flow) and VE (volumetric efficiency) are your main airflow models. found within the Airflow tab in the general section.

[ECM] 12160 - MAF Airflow vs. Output Frequency: This table is used to calibrate the MAF sensor. The MAF sensor works by outputting a frequency signal that is proportional to the airflow through the meter. This table is used to lookup the Airflow (g/sec) value for a given frequency and ultimately calculate the Airmass (g/cyl) used for fueling calculations. If you modify your MAF meter you will likely have to modify this table.

[ECM] 12350 - Primary VE vs. RPM vs. MAP: This table is used to determine airmass per cylinder in case of MAF failure and also to provide a base airflow value to check for MAF failure. It is also used to provide transient condition correction to the VCM main airmass calculations.

straight from the descriptions at the bottom of my tune file. when you hover over most tables they have a decent description of what they are and do.

[Oleblu]

I would check your distributor drive gear for wear. Mine went bad on my 1997 Express in under 100K miles to the point it was misfiring and bucking at highway speeds.

As for the 0411 swap, I would recheck all your wiring. You could have something pinned wrong. If for example you had an injector pinned wrong or the 02 sensors swapped it would run terrible.

That being said my Express ran MUCH SMOOTHER with the 0411 stock tune than the tuned Black box. My Express van has had an idle shudder that feels like a misfire for as long as I can remember (My parents bought it in 1998 with like 11K on it). I actually got so tired of it shuddering with such a mild cam, that I threw a much larger cam in it, just so that I had an excuse in my mind for it to run that way!

Very smart thing to do it just hit me like a ton of feathers, maybe this is why I have the very occasional highway cutout during constant light throttle driving. The engine will completely cutoff then recover almost instantly, very intermittent its been a devil for me to diagnose.

We have to keep in mind fellas, when we swap a pcm on a vehicle that's 20 or so years old some wires might already be partially damaged due to weather, time and previous repairs that could have been made. A couple months back I lost the power reference to my cam sensor and maf including whatever else that 12 volt reference goes to. I had to find an existing ignition wire with a good 12 volt reference and rewire it into my 12 volt reference bundle within the harness. Wires don't always look ir feel broken but sometimes they are failing internally.

[Tparkhill]

Only thing I see different,.. I'm running bout 21-22 degrees spark at idle, whereas, yours is saying 17 degrees.

Hutch, I just looked at my tune and its just like yours. there's a base idle for park and in drive. as soon as I put it in drive its at 23*

[Tparkhill]

Maf (Mass air flow) and VE (volumetric efficiency) are your main airflow models. found within the Airflow tab in the general section.

[ECM] 12160 - MAF Airflow vs. Output Frequency: This table is used to calibrate the MAF sensor. The MAF sensor works by outputting a frequency signal that is proportional to the airflow through the meter. This table is used to lookup the Airflow (g/sec) value for a given frequency and ultimately calculate the Airmass (g/cyl) used for fueling calculations. If you modify your MAF meter you will likely have to modify this table.

[ECM] 12350 - Primary VE vs. RPM vs. MAP: This table is used to determine airmass per cylinder in case of MAF failure and also to provide a base airflow value to check for MAF failure. It is also used to provide transient condition correction to the VCM main airmass calculations.

straight from the descriptions at the bottom of my tune file. when you hover over most tables they have a decent description of what they are and do.

Thanks oleblu, I had an idea what they did I was more asking about when I should modify these tables. I have a separate tuning software solely for Buick's 3800 engines lol. In that software you simply just increase the numbers in the MAF table to add more fuel to MAF. Is that the same on HPT?

[5FDP]

Same concept as DHP software.

You add airflow to the MAF to add in more fuel or the other way around if you remove airflow from the curve to remove fuel.

VE is the same.

[Tparkhill]

Same concept as DHP software.

You add airflow to the MAF to add in more fuel or the other way around if you remove airflow from the curve to remove fuel.

VE is the same.

Thanks.

[Hutchinson]

Give us an update on what you've tried/results bud. I see from your sig that you've installed the upgraded MPFI spider. That should've also helped idle smoothness.

Thing that's stumping me is you only developed this issue after you swapped to the 0411,....leads me to think it's linked to wiring or PCM/tune issue.
Before doing the OS/tune swap in the PCM,.....check to assure a pin/wire connection at the PCM Didnt work loose during your 0411 swap. Check all your ignition related wires for any looseness,....with an ohm meter (if you can). Pull both connectors off the PCM and look at each pin (on the "connection to PCM" side) and assure one of your pins didn't get pushed back up into the connector,....you should be able to see the silver pins butted flush up with the end of the connector (all equal).
Do this test with the meter set on the "ohms setting", not the "continuity" setting.
I'm sure you already know how to do this,...if all looks good at the PCM connector end (all butted up/none pushed back up in the connector) disconnect the wiring/pin from the PCM connector, then pull the corresponding sensor/end connector and slap a meter between them,...while slightly wiggling the pin on the PCM end (do same on sensor/end connector),.....that'll test if the pin has worked loose/not making best contact,....your meter reading will jump all over the place if it's a bad/loose connection,...or show higher reading if there's any corrosion (per below).
When testing on a good wire/pin/connector, the "ohms setting" will show a steady/close to zero ohms (may show 1-3 ohms, which is ok),...but anything more than this would show a possible corrosion issue in the wire itself (hole in the wire insulation somewhere), or corrosion at the PCM pin or sensor end connector. If meter reading jumps all over the place, while your wiggling the wires/pins/connector,...it's showing you have a loose connection. And, of course, if no ohms reading during testing,...... sum-ting-Wong (broke).

Let us know how you faired out.