Tuning Symptoms Sticky Idea
Tuning Symptoms Sticky Idea I've been around awhile and see many many threads repeated about tuning issues on a modified car. Hell, I've created some of the threads lol. What always seems to be missing from the sticky's is a symptoms section that basically says, if you're experiencing ABC, take a look at XYZ. It would seem to be extremely useful to new tuners or people trying to tune their own stuff to list topics or symptoms and then a few things to go check or links to threads where the fix was solved. This can exclude mechanical issues (i.e. vacuum leak, etc.)
Some examples:
Symptom-car smells like fuel.
Investigate- car running rich. Injector data incorrect or VE/MAF table is off.
Symptom- Exhaust burning eyes. Injector data incorrect or VE/MAF table is off.
Investigate- car running lean.
Symptom-60 LB injector swap and running super rich no matter what the IFR is scaled to.
Investigate- B9021 minimum transient pulsewidth table that is hidden unless the cax file is added.
Symptom- car will not hold idle after cam swap.
Investigate-
1. injector data
2. VE/MAF tables
3. Desired Airflow table.
Symptom- car bucks at low rpm in gear.
Investigate-
1. timing too high or too low.
2. airflow values incorrect for throttle cracker/follower.
What do you think? Can we collect a large list of general symtoms and where to usually look for the problem?
Some examples:
Symptom-car smells like fuel.
Investigate- car running rich. Injector data incorrect or VE/MAF table is off.
Symptom- Exhaust burning eyes. Injector data incorrect or VE/MAF table is off.
Investigate- car running lean.
Symptom-60 LB injector swap and running super rich no matter what the IFR is scaled to.
Investigate- B9021 minimum transient pulsewidth table that is hidden unless the cax file is added.
Symptom- car will not hold idle after cam swap.
Investigate-
1. injector data
2. VE/MAF tables
3. Desired Airflow table.
Symptom- car bucks at low rpm in gear.
Investigate-
1. timing too high or too low.
2. airflow values incorrect for throttle cracker/follower.
What do you think? Can we collect a large list of general symtoms and where to usually look for the problem?
Yeah, I even created a sticky like this on the HPTuners
'board. Never really did take off, but a few good bits
have built up. Really depends on the community to make
useful contributions.
If somebody collects it, I will sticky it.
'board. Never really did take off, but a few good bits
have built up. Really depends on the community to make
useful contributions.
If somebody collects it, I will sticky it.
I would love to see more of this, as well as, how to really use and interpret logs. I think a lot of it would fall into place more for me, if I knew more about logs. I mean, I can make them, and get some general, "it's rich here" and stuff, but I mean the real nuts and bolts stuff.
Do you have a link to yours on the HPT site?
TECH Senior Member
Joined: Apr 2002
Posts: 6,080
Likes: 17
From: So.Cal.
This is not so easy because various problems can show the same symptoms and vice-versa, they form a 3D matrix.
I just recently had this:
on a truck conversion, the LTFT's were pegging positive and the MAF was definitely under-reporting, so we thought "ah-ha"... we swapped the MAF and the same thing happened... so we spent a few days looking at the tune, checking for airleaks, swapping O2's, swapping injectors, swapping ECM's, and pulling our hair out...
then while laying clueless under the truck, someone mentioned that a heavy duty diesel air filter has been fitted... so we took a closer look at it (it was a double row ultra dense paper filter, could not see sunlight thru it... interesting filter, what is this actually for...?)... we swapped to a simpler filter, and bingo, now the MAF reported correctly and the trims fixed themselves up.
I just recently had this:
on a truck conversion, the LTFT's were pegging positive and the MAF was definitely under-reporting, so we thought "ah-ha"... we swapped the MAF and the same thing happened... so we spent a few days looking at the tune, checking for airleaks, swapping O2's, swapping injectors, swapping ECM's, and pulling our hair out...
then while laying clueless under the truck, someone mentioned that a heavy duty diesel air filter has been fitted... so we took a closer look at it (it was a double row ultra dense paper filter, could not see sunlight thru it... interesting filter, what is this actually for...?)... we swapped to a simpler filter, and bingo, now the MAF reported correctly and the trims fixed themselves up.
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I hear you Joe, but that is definitely an outlier, I was shooting for more generalities. I.e. Car idles great with a cam once warm but fights and dies when doing a cold star. Check the startup friction airflow table and also make sure it doesn't have too much after start fuel enrichment since the cam isn't efficient at idle.
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I would love to see more of this, as well as, how to really use and interpret logs. I think a lot of it would fall into place more for me, if I knew more about logs. I mean, I can make them, and get some general, "it's rich here" and stuff, but I mean the real nuts and bolts stuff.
Teching In
Joined: Aug 2010
Posts: 18
Likes: 0
From: Mississippi Gulf Coast
Great Idea Great for new guys like me. In fact I am trying to figure out an issue related to the first post. Car running rich. STFTs are between -8 and +5, however LTFTs are 24 and 25. Not sure which direction to go first. I am guessing I need to find out what is telling the PCM I have a lean condition...I sent the PCM off to TPIS and had a base tune built for it based on my data just to get the car to run safely, however it is on the rich side. My guess is the problem is not so much the tune but engine/sensor related.
Any help would be appreciated. I am going to do a search next.
Any help would be appreciated. I am going to do a search next.
Yes, PLEASE bring this thread to life. So much learning potential with this kind of thread... Maybe thats why noone is posting.. possibly giving aways some guys way of making money...
I post in the tuning section almost every day helping people for free. I doubt anyone is worried about helping anyone and not making money. The sticky is a good idea in theory but very hard to make work IMO is the reason is hasn't taken off.
I disagree that this thread would be tough to make work. I would have no issue updating my first post whenever someone posts some insight in the format I provided above. Yes there is no guaranteed be-all end-all fix for a symptom, but there are general rules and guidelines to look out for, or at least a process of elimination to follow.
Moderator
Joined: Aug 2010
Posts: 7,323
Likes: 529
From: Ann Arbor, MI
There are a bewildering number of different and unique questions asked in this Tuning section and it already has a huge Sticky section, perhaps too big.
I therefore tend to agree with LSX that it would be a huge effort and not that likely to be beneficial. Most people would just start new threads anyway and that is OK.
While a new moderator in this section, I am certainly no tuning expert. However when I see a new thread go unanswered, I try to post something (hopefully) half-intelligent to both bump it to the top and start the conversation. It has worked well in the Auto-Trans section where I have been the primary poster for years and now also a moderator.
Experts like LSX are incredibly generous with their time and knowledge.
If I see the same questions come up again and again, I will address it, perhaps with a sticky. I do think most people Google their question and Google does a good job of linking them to the best threads; much better than the primitive search function built into the forum.
I therefore tend to agree with LSX that it would be a huge effort and not that likely to be beneficial. Most people would just start new threads anyway and that is OK.
While a new moderator in this section, I am certainly no tuning expert. However when I see a new thread go unanswered, I try to post something (hopefully) half-intelligent to both bump it to the top and start the conversation. It has worked well in the Auto-Trans section where I have been the primary poster for years and now also a moderator.
Experts like LSX are incredibly generous with their time and knowledge.
If I see the same questions come up again and again, I will address it, perhaps with a sticky. I do think most people Google their question and Google does a good job of linking them to the best threads; much better than the primitive search function built into the forum.
Then perhaps what is needed is a freshing of the stickies in this section. All of the links from "horist" stickies are dead since his site is no longer active. Also, the current stickies tell you some good, basic tuning info, not how to troubleshoot. That was my intent with this thread, was helping people who have already tried tuning their cars to troubleshoot a problem.
Symptom: Swap in a new MAP sensor unlike your prior one and the engine ..
a. Starts then dies
b. Runs lean
c. Runs rich
Cause(likely): MAP Linear/Scalar and/or Offset is incorrect.
Just ran into this on my own car. Bought a '3 bar MAP sensor' (AC Delco 12623671) and converted (with my HPTuner Pro software) to the 3bar operating system. HPTuners changes the default Linear to 305, leaves the offset at 10.xx. Result, it would start but die, running very lean. Not knowing about the Linear and offsets relationship, I tried changing the IC (injector constant) and VE all over the place to get her to idle. But though it would weakly idle, any gas pedal made it stumble and run irregularly, plus lean backfire.
After searching the net, I accidentally found the MAP Linear and Offset context. I played around with that after resetting the IC and VE to their initial values. Using 333.33 and 38 for the Linear and offset, it idles fine and accepts throttle responsively. I've since heard from several sites that this is not the best MAP sensor for my car, so I ordered a new plug and play 3 bar sensor that has a better reputation.
a. Starts then dies
b. Runs lean
c. Runs rich
Cause(likely): MAP Linear/Scalar and/or Offset is incorrect.
Just ran into this on my own car. Bought a '3 bar MAP sensor' (AC Delco 12623671) and converted (with my HPTuner Pro software) to the 3bar operating system. HPTuners changes the default Linear to 305, leaves the offset at 10.xx. Result, it would start but die, running very lean. Not knowing about the Linear and offsets relationship, I tried changing the IC (injector constant) and VE all over the place to get her to idle. But though it would weakly idle, any gas pedal made it stumble and run irregularly, plus lean backfire.
After searching the net, I accidentally found the MAP Linear and Offset context. I played around with that after resetting the IC and VE to their initial values. Using 333.33 and 38 for the Linear and offset, it idles fine and accepts throttle responsively. I've since heard from several sites that this is not the best MAP sensor for my car, so I ordered a new plug and play 3 bar sensor that has a better reputation.
Last edited by mightyquickz28; Dec 31, 2015 at 03:47 PM.
Haha good post, I saw the first sentence about swapping map and the car not running and immediately though tune for the offset and scalar. Nice addition. We need more people adding to this.
Teching In
Joined: Jan 2016
Posts: 13
Likes: 0
From: Livingston
Tuning Im new, but people like you are a big help. Most tuners wont help, im $700 in mt tune and still having issues. This thread would help cause IDK what to do now. Seem slike tuners friends get the hook up and the rest get an upload.
