whats up guys,
recently converted my car to obd1 have all obd1 conversion parts. when i start the car when cold the idle fluctuates, and when warmed it idles rough and lag under full throttle up to 4k rpm. i have tried 3 different distributors and 2 ecus both were chipped to run no o2 sensor so i dont have an o2, but i have also tried adjusting the idle at iacv and made somewhat of a difference when i unplugged the iacv to adjust screw the idle did drop a lot so assuming it works. car runs fine with the obd0 stuff on which makes no sense to me at all.
that was my next guess. but would a vacum leak be able to cause it to bog that bad ? even when it runs a lot better with the obd0 stuff on ?
ecu is a chipped p28 with non vtec map for my b20b also tried to different td55 dizzys and a chipped p75 with a b20 map on it.
im really stumped man any input greatly appreciated
Basemaps are usually just a rough guess as where the motors fuel curve is. Mine runs like shit right now on a basemap that I’m only assuming will clear up with my tune.
In for the thread as I’m curious if there are any external sources of this problem, but my money is on the basemap.
Of course, the relative question is which motor is it on. There is no factory fuel map for an ls/v. And IIRC, you cannot cross map different motors with identical outputs.
[QUOTE=AxeOfGlory;2299844]Basemaps are usually just a rough guess as where the motors fuel curve is. Mine runs like shit right now on a basemap that I’m only assuming will clear up with my tune.
In for the thread as I’m curious if there are any external sources of this problem, but my money is on the basemap.
Of course, the relative question is which motor is it on. There is no factory fuel map for an ls/v. And IIRC, you cannot cross map different motors with identical outputs.
Brandon[/QUOTE]
its from a reputable tuner around here though, probably almost all of the people around here are using richtuned maps with no problem.
but i also agree with you on the basemap thing i know its not good for long term use, it was supose to be temp anyways just to convert for the rest of the turbo stuff.
but i really think it might be a vacumm leak, when i cover the iacv port on the throttlebody it just keeps running at like maybe 200 rpms.
You have a lot of variables to consider, and we don’t know if you just swapped in a motor from an importer or did a rebuild, if you did any maintenance to the motor before installing…etc
spark plugs, are they new? gapped correctly?..etc
spark plug wires, could be part of the problem, but I doubt it, they rarely go bad
fuel filter
fuel pressure - what is your fuel pressure?
injectors, if these are old or have been sitting for a long time they could be clogged
mechanical timing - the bogging you speak of sounds very similar to when you have the mechanical timing off by a tooth or two.
ignition timing?
clean IACV, replace gaskets/seals
are you running a FITV? do you need one?
DO NOT adjust the idle screw on the throttle body, this should only be used as a last resort to fine tune your idle if absolutely needed
consider getting an O2 sensor, I don’t know why you’re not using one now
burp the cooling system, bouncing idle issues can often result from air in the cooling system
[QUOTE=Colin;2299868]You have a lot of variables to consider, and we don’t know if you just swapped in a motor from an importer or did a rebuild, if you did any maintenance to the motor before installing…etc
spark plugs, are they new? gapped correctly?..etc
spark plug wires, could be part of the problem, but I doubt it, they rarely go bad
fuel filter
fuel pressure - what is your fuel pressure?
injectors, if these are old or have been sitting for a long time they could be clogged
mechanical timing - the bogging you speak of sounds very similar to when you have the mechanical timing off by a tooth or two.
ignition timing?
clean IACV, replace gaskets/seals
are you running a FITV? do you need one?
DO NOT adjust the idle screw on the throttle body, this should only be used as a last resort to fine tune your idle if absolutely needed
consider getting an O2 sensor, I don’t know why you’re not using one now
burp the cooling system, bouncing idle issues can often result from air in the cooling system[/QUOTE]
spark plugs are new and gapped to .043 if i remember right
bought new wires and didnt fix it.
checked ignition timing and it was dead on
am running a fit valve everything is stock.
in my first post i stated that i only converted from obd0 to obd1 and it started happening. it runs pretty much fine when i plug back in the obd0 ecu and distributor
Well, sounds like you’ve answered your own question then. Sounds like you are using adapter harnesses’ and that’s how you could easily swap back to the OBD0 ecu and distributor? And you’ve tried multiple OBD1 ecu’s and multiple OBD1 distributors. That pretty much narrows it down to a problem with the wiring. Time to break out the pen, notepad, continuity tester and OBD0 and OBD1 wiring / pinout diagrams.
*I’m assuming your ecu basemaps came from different sources and the bogging and strange idle problems are exactly the same with both ecus. If this is the case then you can probably rule out it being an ecu or basemap problem. If your ecu’s have basemaps from the same source then I would not rule out the ecu as the problem. I’d get a STOCK ecu and try that. It’ll throw a code for not having an O2 sensor, but it’ll just run off predefined values which should not result in idle problems or bogging.
**You said it runs “pretty much fine” when you go back to OBD0. Does that mean the problem goes away or it just isn’t as bad? There’s a HUGE difference in what direction your troubleshooting will take depending on the answer to that question.
[QUOTE=Colin;2299880]Well, sounds like you’ve answered your own question then. Sounds like you are using adapter harnesses’ and that’s how you could easily swap back to the OBD0 ecu and distributor? And you’ve tried multiple OBD1 ecu’s and multiple OBD1 distributors. That pretty much narrows it down to a problem with the wiring. Time to break out the pen, notepad, continuity tester and OBD0 and OBD1 wiring / pinout diagrams.
*I’m assuming your ecu basemaps came from different sources and the bogging and strange idle problems are exactly the same with both ecus. If this is the case then you can probably rule out it being an ecu or basemap problem. If your ecu’s have basemaps from the same source then I would not rule out the ecu as the problem. I’d get a STOCK ecu and try that. It’ll throw a code for not having an O2 sensor, but it’ll just run off predefined values which should not result in idle problems or bogging.
**You said it runs “pretty much fine” when you go back to OBD0. Does that mean the problem goes away or it just isn’t as bad? There’s a HUGE difference in what direction your troubleshooting will take depending on the answer to that question.[/QUOTE]
the basemaps are from the same source ecus are from different sources. right now i have a chipped p28 from a reputable tuner in the area.
with what i said earlier about it being pretty much normal. it pulls and doesnt lag or is atleast alot less noticable.
i have a question though is i want to know if a vacum leak can cause both of these symptoms. i know it can cause the idle issue, but what about the bogging and stuttering.
and thanks colin for all the ideas and help really appreciate it.
Well, that makes it so you cannot rule out the ECU as your problem. Find a stock ecu to test so you can rule out the ecu.
Take another drive and think about it a little harder. If the problem is GONE then you can rule out everything on the motor and is HAS to be related to the OBD1 conversion. If the problem is still there, then the problem could be coincidental and the symptoms are different with different ECU’s (obd1 vs obd0). It’s important you figure this out because it will greatly change what items you are troubleshooting.
In my experience, no. At idle a vacuum leak should increase idle, not make it rough. The idle is increased because you are letting more air into the motor, exactly the same concept as opening the throttle body except the air is getting in thru the vacuum leak. With that said, you could have idle problems if that leak is affecting how an idle control component is functioning. And I think you’d have to have a HUGE leak to have any sort of issues once you get into the higher rpms. At idle the engine isn’t pulling in a lot of air, so a small leak is a significant amount of air compared to the total amount of air getting into the engine. At more wide open throttle positions the leak would only provide a very very small amount of air compared to the air getting in through the throttle body, so the effect should be minimal if it’s noticeable at all. However, again, if the leak is causing some other component to function incorrectly then you have a whole host of other possible symptoms. Regardless of all of that, if you swap back to an OBD0 ecu and dist and the problem goes away this would indicate the problem was not a vacuum leak since the problem should persist.
I think you really need to start looking at this a little more scientifically and methodically. Write a list of the possible options and start crossing them off one by one as you test and troubleshoot. Right now the list of potential things is nearly limitless, start narrowing them down starting with the easiest items to rule out and the items which are the most obvious possible culprits. Progressively move towards items which are harder to troubleshoot and are less likely the source of your problem.
[QUOTE=Colin;2299885]Well, that makes it so you cannot rule out the ECU as your problem. Find a stock ecu to test so you can rule out the ecu.
Take another drive and think about it a little harder. If the problem is GONE then you can rule out everything on the motor and is HAS to be related to the OBD1 conversion. If the problem is still there, then the problem could be coincidental and the symptoms are different with different ECU’s (obd1 vs obd0). It’s important you figure this out because it will greatly change what items you are troubleshooting.
In my experience, no. At idle a vacuum leak should increase idle, not make it rough. The idle is increased because you are letting more air into the motor, exactly the same concept as opening the throttle body except the air is getting in thru the vacuum leak. With that said, you could have idle problems if that leak is affecting how an idle control component is functioning. And I think you’d have to have a HUGE leak to have any sort of issues once you get into the higher rpms. At idle the engine isn’t pulling in a lot of air, so a small leak is a significant amount of air compared to the total amount of air getting into the engine. At more wide open throttle positions the leak would only provide a very very small amount of air compared to the air getting in through the throttle body, so the effect should be minimal if it’s noticeable at all. However, again, if the leak is causing some other component to function incorrectly then you have a whole host of other possible symptoms. Regardless of all of that, if you swap back to an OBD0 ecu and dist and the problem goes away this would indicate the problem was not a vacuum leak since the problem should persist.
I think you really need to start looking at this a little more scientifically and methodically. Write a list of the possible options and start crossing them off one by one as you test and troubleshoot. Right now the list of potential things is nearly limitless, start narrowing them down starting with the easiest items to rule out and the items which are the most obvious possible culprits. Progressively move towards items which are harder to troubleshoot and are less likely the source of your problem.[/QUOTE]
if the jumper harness had something wrong with it or mis wired or something dont you think there would be a cel of some sort ?
when i am running the car i have plugged the iacv port on the throttlebody and the car keeps running for about a minute or two before it shuts off.
also when i start the car when it is cold on the obd1 ecu and distributor the idles starts off at 2k or so then it wold hold for about thirty seconds, then it will drop all the down bog for a couple seconds then jump right back up to 2k. doesnt do this when i run obd0 ecu and obd0 distributor
Not necessarily, these older cars aren’t like new cars where every little thing turns on the CEL, lots of stuff can be wrong and no light will go on.
[QUOTE=DAman9;2299891]when i am running the car i have plugged the iacv port on the throttlebody and the car keeps running for about a minute or two before it shuts off.
also when i start the car when it is cold on the obd1 ecu and distributor the idles starts off at 2k or so then it wold hold for about thirty seconds, then it will drop all the down bog for a couple seconds then jump right back up to 2k. doesnt do this when i run obd0 ecu and obd0 distributor[/QUOTE]
Why are you “plugging the iacv port”? I don’t understand what you’re trying to troubleshoot. And what do you mean when you say you plug it? Did you remove the iacv and plug the holes in the manifold? Maybe I’m just forgetting what the non vtec ones are like but on my car there’s nothing you can “plug”. Have you thoroughly read the section in your Helms manual on the Idle control components so that you inderstand how the system works, what symptoms failures will result in, and some of the troubleshooting procedures?
[QUOTE=DAman9;2299891]when i am running the car i have plugged the iacv port on the throttlebody and the car keeps running for about a minute or two before it shuts off.
also when i start the car when it is cold on the obd1 ecu and distributor the idles starts off at 2k or so then it wold hold for about thirty seconds, then it will drop all the down bog for a couple seconds then jump right back up to 2k. doesnt do this when i run obd0 ecu and obd0 distributor[/QUOTE]
I would source another jumper harness from a friend or craigslist and see if that changes anything. If the harness is from a reputable company like Xenocron or Rywire then I would think with high probability that the wiring is correct. However, these are hand made and sometimes mistakes do happen.
You can source external vacuum leaks by spraying brake clean when the motor is cold on the vacuum lines. If the idle bursts or increases you have have a vacuum leak. Do not, ever, spray it hot. I’ll give you a Darwin Award.
I agree 100% with bleeding the cooling system, it got rid of my roaming idle. I had a TON of air from my new radiator and fluid flush. It’s a 12mm bolt on the upper coolant hose neck. Crack it until it pisses a steady stream, at operating temp with the heat on high. This will open your entire cooling system.
Make sure you have the overflow filled the specification and the line is not cracked to the container.
Did you say you checked mechanical timing (cam to crank)? If not, check it. Leaking any fluids?
My money is still on the basemap. Call the tuning company and question them about these problems in association to the basemap and see if they will verify it could cause that problem.
Turns out one of the spark plug gaskets took a dump on me soaking the number 1 plug, causing it to idle like Michael J. Fox.
Still curious on your situation though![/QUOTE]
no updates yet, havent had too much time to work on it right now because of my schedule lately. really sucks because i really want to get this figured out.
hopefully updates sometime later this weekend if i find enough time.
I had similar issues with my obd1 converted ls-vtec. Bought the car with swap already done, guy seemed like he knew what he was doing! Spent a TON of time trying to get it to run right. Cleaned the iac, rebuilt fitv, cleaned throttle body, re ran vacuum lines, plugs, wires, coil, new manifold gaskets, cleaned fuel injectors & rail & regulator, checked timing, bled coolant… Everything I could think of. (Found plenty of problems as I did this but none solved the main idle issue)
In the end, when I tried to calibrate the tps I couldn’t get the right voltage. So I bought a new one, same issue. Checked the continuity of the wires back to the ecu. Everything seemed good.
The power and signal wires were switched in the wiring. Due to the way the resistor works in the tps I was still getting a decent output at full throttle, but at idle the ecu thought I was at the half throttle position. Switched the wires, calibrated tps, reset idle, reset the ecu. Now it’s PERFECT!