Car Won't stay running after engine swap

[[ion] C2]

Originally Posted by crankycowboy

I will give this a go and report back. Thanks.

In case you're curious, the reason behind my suggestion:

O2 sensor might suck and is maxing rich occasionally, causing car to pull all fuel til it corrects it. Mine currently is failing and sometimes does this making my car die, lol, even though the tune is perfect and it runs smooth in open loop (no O2 sensor input). My air/fuel ratio bounces around too much lately with the O2 sensor active; it overshoots a lot and is generally annoying due to it maxing rich/lean a lot because it's not moving fast/accurately enough to maintain a proper control on the ratio.

[a.graham52]

Originally Posted by crankycowboy

Thanks, I will exhaust all the other suggestions made here first before going the "dealership" route, ouch!

Speaking of MAF sensor....When I was pulling the air intake "box lid" off I lifted too much and broke one of the tabs that holds it down. Could it be "sucking" air without going through the filter first and causing additional problems, or is that a stretch (I'm sure you can tell I'm grasping at straws at this point).

no, air would still be getting metered through the maf sensor. if air was leaking after the sensor such as the intake gasets etc... then yo uwould have a problem.

[crankycowboy]

Originally Posted by [ion] C2

In case you're curious, the reason behind my suggestion:

O2 sensor might suck and is maxing rich occasionally, causing car to pull all fuel til it corrects it. Mine currently is failing and sometimes does this making my car die, lol, even though the tune is perfect and it runs smooth in open loop (no O2 sensor input). My air/fuel ratio bounces around too much lately with the O2 sensor active; it overshoots a lot and is generally annoying due to it maxing rich/lean a lot because it's not moving fast/accurately enough to maintain a proper control on the ratio.

Thanks for the input. Yeah, the 1999 engine came with a o2 sensor on it, but I had bought the one on there just about 6 months ago, so opted to put that one back on; however, I have heard that occasionally in engine swaps etc...rtv/silicone can cause o2 sensors to go downhill so I'm not ruling anything out at this point. My biggest problem is twisting someones arm to come over as I have to keep my foot on the gas anytime I try to do something while running otherwise it obviously dies. But in this case, I'll unplug and see what happens. I did the same thing to the MAF and it didn't effect idle, just ran worse....lol

[a.graham52]

does it run nice and smooth when you hold the throtle at "idle speed"? could be the IAC valve acting up even though you said it cycles.

[crankycowboy]

Originally Posted by a.graham52

does it run nice and smooth when you hold the throtle at "idle speed"? could be the IAC valve acting up even though you said it cycles.

It does run nice and smooth as long as I keep my foot on the gas. It also revs fine and accelerates great when driving. It's really just the idle that's the problem. When I take my foot off the gas it dies immediately (usually), but I have noticed if I let it run for a long period in the driveway, it will sort of "sputter" before dying....so maybe driving it would help. In regard to the IAC valve...that would be my first guess...but I actually had another one from the engine I bought (i used the intake off the previous engine), and I tried it....with same results.

[AleroB888]

Originally Posted by crankycowboy

Good point. I haven't done anything to the PCM, which is why I thought my question regarding "re-learning" was valid. I used most of the components from the 2003 motor (fuel rail, injectors, cps, all the sensors etc....so I think I should be good?

As long as you're reaching, you could try switching both '99 cps's back.

[crankycowboy]

Originally Posted by AleroB888

As long as you're reaching, you could try switching both '99 cps's back.

Well as mentioned a couple of posts back, there are just a few differences between the 2003 and the 1999. The CPS was one of them. The connector that plugs into the wiring harness is different so I couldn't connect it and I couldn't splice in the connector because the 2003 the connected is directly on the sensor opposed to having leads coming off (meaning there are no wires).

[crankycowboy]

Ok, well I got home and took the car for a drive on the highway. I drove about 13 miles. When I got back and pulled into the driveway, the car died the minute I took my foot off the gas I tried disconnecting the o2 sensor as was suggested which didn't have any noticible difference. I did notice however, if I don't just take my foot off the gas and sort of ease the rpms down....that it will stay running (roughly), where rpms will drop down to around 500 or less and then bump up (where it's obviously trying to keep itself running), it will bump up and down like that for about 60 seconds until finally it will lose it and die. I'm sort of running out of things to try. Any other ideas short of taking it to the dealer as was suggested? Does it need to be driven further for the computer to relearn? I put my code reader on there and it's saying all systems aren't ready yet....so do I need to drive it until everything is in "ready" status?

[[ion] C2]

probably vacuum leak then

there's no "relearn" that can fix this shit. this is a mechanical/electrical problem, not PCM

[AleroB888]

You could try introducing a small air bypass around the throttle body, route a hose with a flow restrictor to loop around it, see if it maintains an idle. May be a VE difference between the 2 engines at idle.

[crankycowboy]

Originally Posted by [ion] C2

probably vacuum leak then

there's no "relearn" that can fix this shit. this is a mechanical/electrical problem, not PCM

Believe me, I'm not a COMPLETE idiot, and this stupid thing has me scratching my head. There are only a couple places that require vacuum that effect the idle, right? Where do you suggest I check?

[crankycowboy]

Originally Posted by AleroB888

You could try introducing a small air bypass around the throttle body, route a hose with a flow restrictor to loop around it, see if it maintains an idle. May be a VE difference between the 2 engines at idle.

I'm sorry AleroB888, I'm up for trying anything...I'm just not completely sure what you are suggesting, can you please elaborate?

[AleroB888]

Originally Posted by crankycowboy

I'm sorry AleroB888, I'm up for trying anything...I'm just not completely sure what you are suggesting, can you please elaborate?

There is a certain amount of air leakage past the throttle plate. Some throttle plates also have a small hole drilled in them to fine tune that amount. Rather than add or enlarge a hole in the throttle plate, you could try looping a vacuum hose around the throttle body.

I know the IAC is supposed to compensate for that, but I have run into situations in modded setups especially, where it still needed more air.

The PCM should command 20 degrees of timing with the TPS at zero percent, throttle plate closed. What parameters are you able to read on your scanner?

What I am suggesting is something just to get it drivable untill you can research it more. Engine/PCM interactions can be frustrating.

[a.graham52]

call a local dealer and ask how much to do the crank relearn proceadure.

[crankycowboy]

Ok guys, I have a question...I may be on to something. Can the throttle cable "stretch"? I noticed some "play" in the cable at idle, and we kept saying it was sounding like maybe the "butterfly" was closed too much and choking it out. So I took a piece of vacuum hose and sliced it down the center and put it over the accelerator cable (so that there was more tension from the get-go). And wala.....the car starts without me having to put my foot on the gas and idles beautifully (just under 1k), smooth and quiet. Now, obviously this is a "band-aid", but could it be the throttle cable? What else could be the "real" problem? Please see attached picture for the temp solution.

[AleroB888]

Originally Posted by crankycowboy

Ok guys, I have a question...I may be on to something. Can the throttle cable "stretch"? I noticed some "play" in the cable at idle, and we kept saying it was sounding like maybe the "butterfly" was closed too much and choking it out. So I took a piece of vacuum hose and sliced it down the center and put it over the accelerator cable (so that there was more tension from the get-go). And wala.....the car starts without me having to put my foot on the gas and idles beautifully (just under 1k), smooth and quiet. Now, obviously this is a "band-aid", but could it be the throttle cable? What else could be the "real" problem? Please see attached picture for the temp solution.

If it is, that would be the throttle plate clearance I mentioned. It has an adjustable stop, but you can not open it up so far that the TPS reads more than zero degrees when closed. Hence also why some plates have a hole drilled.

Also, the throttle cable does not hold the plate open at idle, it should have a tiny bit of slack.

[xXManwhoreXx]

So I was right! Muahaha..

There should be some kind of screw to tighten the cable but idk ive never messed with the tb on my ho

[a.graham52]

Originally Posted by AleroB888

Also, the throttle cable does not hold the plate open at idle, it should have a tiny bit of slack.

x2 therefore i think what your doing is just holding the throttle plate open compinsating for the real issue.

[crankycowboy]

Originally Posted by AleroB888

If it is, that would be the throttle plate clearance I mentioned. It has an adjustable stop, but you can not open it up so far that the TPS reads more than zero degrees when closed. Hence also why some plates have a hole drilled.

Also, the throttle cable does not hold the plate open at idle, it should have a tiny bit of slack.

AleroB888, I said a few posts back that I wasn't a COMPLETE idiot...I may have to retract that statement. I guess through all the times that I have had this thing on and off that I never noticed there was a physical stop (I assumed the length of the cable controlled the stop and the IAC controlled the rest). I had an extra throttle body, so I looked at it and now I feel really stupid (see attached pic, just in case it helps someone else). I did notice that there is a lot of "play" where the cable mounts to the "bracket". I can grab the cable and move it in and out and either rev it or kill it just by the amount of play there is where it secures to the bracket....so maybe with me pulling it off and on a 100 times, caused this? How do you suggest I adjust things as it appears that I can't access it while on the car, or can I? Thanks a lot guys for sticking with me through this mess and sorry to have to point out how dumb I apparently am.

[AleroB888]

Originally Posted by crankycowboy

AleroB888, I said a few posts back that I wasn't a COMPLETE idiot...I may have to retract that statement. I guess through all the times that I have had this thing on and off that I never noticed there was a physical stop (I assumed the length of the cable controlled the stop and the IAC controlled the rest). I had an extra throttle body, so I looked at it and now I feel really stupid (see attached pic, just in case it helps someone else). I did notice that there is a lot of "play" where the cable mounts to the "bracket". I can grab the cable and move it in and out and either rev it or kill it just by the amount of play there is where it secures to the bracket....so maybe with me pulling it off and on a 100 times, caused this? How do you suggest I adjust things as it appears that I can't access it while on the car, or can I? Thanks a lot guys for sticking with me through this mess and sorry to have to point out how dumb I apparently am.

Did you use the original throttle body, upper intake, and same type gasket? If not, it is possible the flange opening for the IAC got accidently obstructed.

You may have a couple turns of adjustment possible on the screw before it goes out of spec (more than zero degrees). There is also a TPS relearn, iirc., but not usually needed.

Compare the two throttle body blades (does either or both have a hole drilled?), and are the mounting flanges the same?

The return spring on the throttle body is stronger and overrides the gas pedal return spring. The car should idle even with the cable off.

I don't think it's anything you caused, but looks difficult to adjust in the stock location. Can you get a flat feeler gauge to prop open the set screw slightly, while checking the TPS readout?