Throttle body issues

[Sawboo]

My car is a 92 laser awd. The previous owner had had lost/broke the biss screw and just ground down a bold and jammed it in the hole. The TPS was out of adjustment, (showing 5% on the logger at idle) but the car ran, just lean at idle.

A couple weeks ago I adjusted the TPS to read 10% at idle but now the car wont stay alive. I figure the ghetto-biss must be the problem and rip it out to replace it with a factory biss to find the hole is stripped.

I ordered a used tb for a 92 laser from the classifieds but it didnt have a spot to bolt on the tb elbow. It was just a straight pipe and wont work with my stock setup. (stock uicp and tb elbow)

So now my car has been sitting for 2 weeks an im ready to try to retap the biss hole and just grind down a new bolt to the right size.

Does this sound like a terrible idea?

 

[92AWDHX40]

Get another tb, throttle biss damanged find another tb, classifies, ebay, i see them all over cheap.

 

[1990AWD]

sounds like you got a n/t throttle body; anyways, I would try to make it work, the n/t TBs are actually a slight upgrade.

 

[Sawboo]

Yes the tb looks almost perfect but the part where my piping attaches on will never work. It also doesn't seem like I could get an elbow coupler/reducer that would fit without relocating my battery.

I went ahead and tapped the biss hole out to 10mm and the OEM biss screws works perfectly again, but the car still idles really erratic and sometimes dies. My logger shows the ISC bouncing around 90-110+(no matter how the biss is adjusted.) I understand this is high so I probed terminals 1-2 on the ISC as per the shop manual and my original TB reads 41 where the new TB I received reads 30. The manual said anywhere between 28 and 33.

When I removed my TB originally to adjust the TPS my friends sprayed it down really well with TB cleaner and I told him he needed to plug the holes first but he didnt.

So I guess my question is/are:

Could the ISC have been damaged from the cleaner?
and
Could the resistance being to high on the ISC cause the car to search endlessly for its idle loping up ap and down between 500 and 100 rpms?

Thanks tuners, you da best.

 

[LiquidX]

First off, you should be reading 0% throttle at idle. You don't have your foot on the gas pedal when you idle, think about it.

To set the BISS, you need to ground the diagnostic pin on the data port. That prevents the ICS from countering your attempts at setting the proper RPM. If you cannot tell the ECU what RPM you wish to idle at then you should be setting it to 750rpm. With it set to 750 via the BISS, the ICS should be in the proper value range since the ECU is trying to maintain a 750rpm idle through it's coding.

Also any boost leaks will mess up your readings too.

 

[1983gsp]

On a 1g, tps should read 10% at idle.

 

[Sawboo]

Thanks for the info guys. So just to clarify, No matter where I have the biss screw set the isc will hover at a minimum of 90 on the logger.

So either the ISC is faulty (based on the high resistance) causing it to just run high and cause alot idle problems or could these problems be caused by an intake leak?

The car was working fine, all I did was pull the TB, adjust the TPS to 10%, clean TB without stuffing holes, and reassemble and try to start resulting in the car not being able to idle.

I've even set the TPS back to 5% like it was originally and am still having the same problems.

bad isc?

edit: Ive read the ISC's are the same on n't and turbo dsms, but my original ISC has 2 screws and the used TB I ordered has 3

 

[92AWDHX40]

Terry's Talon Troubleshooting Tips #3 - Fast Idle (aka. Idle Surge)


no surge this may help though.

 

[BoostedBeaver]

On a 1g, tps should read 10% at idle.

The TPS Should be at .48-.52 volts at idle. You can test this by unplugging and probing the TPS pins to obtain a voltage reading. Since you believe you have this set properly, checking it should be a breeze. If you find it out of wack adjust the TPS until you reach the correct volts.

The ISC should hover around 30. Ground the timing connecter and diagnostic port. This will take away the control of the ISC. Screw the BISS in or out to adjust the RPM's to 750. Once this is achieved, you should receive a more proper reading.

 

[Sawboo]

ok I will ground the ISC and set the idle with the biss accordingly. Im still getting mixed answers about the TPS values.

As I understand the TPS runs on a 5v circuit and at idle (0% throttle) the TPS should read approx 0.5v which equates to 10% on a data logger.

Can anyone confirm?

 

[curt-s]

I don't run it yet, but it appears to be a difference of values if you're running DSMLink or not.

http://www.dsmtuners.com/forums/newbie-forum/407363-1g-throttle-body.html#post152638704

 

[1990AWD]

When using ECMLink, setting it at .63V equals 0% throttle, and 5.00V equals 100% throttle, however, I do remember reading in the FSM that is should be .48-.52V, but I think that was for the '90 TPS.

 

[Sawboo]

I'm using mmcd. The car used to run set at 5%. Doesnt run at 5% now. Well at least not very well.

 

[steve]

Not sure how you obtained this information but to all of my knowledge this is wrong. The TPS Should be at .63 volts at idle. You can test this by unplugging and probing the TPS pins to obtain a voltage reading. Since you believe you have this set properly, checking it should be a breeze. If you find it out of wack adjust until you read .63 volts.

If the logger is saying 10%, then the computer believes that the throttle plate is open 10%. This is false as the BISS, ISC, and FIAV all let air past the throttle plate for this very reason. Unless this is a fault in the way the logger is transmitting data, 10% at idle is wrong. I suggest pulling out the multimeter and reading the volts from the TPS to be sure.

Sorry, Like 1990AWD said.

1G Specific:

DSMLink likes 0.63v for it's closed TPS voltage but the factory spec is 0.48 to 0.52v. That's about 10% of the 5v fed to the TPS and since 1G dataloggers don't scale the TPS output like a 2G they show the raw %.

 

[TunerJunkie]

Have you checked to make sure you base timing is set properly?? Had an erratic idle on my 90' only to discover my timing so far off it didn't even register on any marks. Set it to 5 degrees and it purred like a kitten afterwards.

 

[Sawboo]

I had set the base time about a month ago so it should be fine unless the cas moved when i removed the bottom nut to remove the tb but I dont think it did.

 

[BoostedBeaver]

Sorry, Like 1990AWD said.

1G Specific:

DSMLink likes 0.63v for it's closed TPS voltage but the factory spec is 0.48 to 0.52v. That's about 10% of the 5v fed to the TPS and since 1G dataloggers don't scale the TPS output like a 2G they show the raw %.

Thank you for clearing that up. I did not know the logger showed a raw volts value for the TPS. Sorry for the misinformation and my post will be altered so that others are not misinformed.

Robert

 

[TunerJunkie]

I had set the base time about a month ago so it should be fine unless the cas moved when i removed the bottom nut to remove the tb but I dont think it did.

I see what your saying but ya never know. It only takes 30 seconds to check it quick and rule that out as a possibility. I was fairly positive mine was set properly too.

 

[Sawboo]

OK so problem solved! Thanks everyone for the help.

Once I grounded the ISC the car would bounce rapidly between 1200 and 1500 rpm. (idle surge)

The BISS wasn't far enough down and made the ISC really struggle/fail to try and keep the rpms under control. I just tightened the BISS down untill I was idling just around 750 and removed the jumper cables to the diagnostic port.

Now all is well! Thank you so much guys.

Also, I regarding the ISC coils reading 40 ohms instead of the 30 like the haynes manual said. I found this on DSMISC.com

9. The new ISC you shipped me reads 40 Ohms across the coils, not 28-33 ohms. This isn't what the VFAQ, or the OEM manual or other test procedures say.
Yes, because most of the on-line info on DSM ISCs is old and has never been updated! Mitsubishi started putting these new ISC's in cars around 2000. Dealers started selling them as OEM replacements for DSMs after they cleared out their stock of the older units. These older units (cast metal/brown plastic) are impossible to find anymore, and in any event, aren't as good as the new version. The new OEM replacement ISC for the 4G63 motor uses a higher ohm load. This is an improvement over the old ISCs, which were suppose to be within spec if they were between 28-33 ohms. Those cause the ECU to push more current. The new-style ISC's are much more precise and will read about 40 +- 0.25 Ohm across each coil. The higher ohm rating is actually a good thing, and results in pushing your ECU drivers less than even a brand new, old ISC. In other words, it uses less power to do the same thing.

Also, 10% is the correct TPS value at idle when using a MMCD Datalogger.

 

[TunerJunkie]

Right on glad you figured it out.