KingsHustleLA

So When I Drive My Car On The Freeway & There's No Traffic It's Fine. But When I'm In Stop & Go Traffic On The Freeway Or Streets After About 20-30 Minutes The Idle Gets Really Sloppy & My Engine Shuts Off. It Will Start Right Back Up But Immediately Repeats The Process. After I Park It, Open The Hood & Let It Cool Off For About 45 Minutes Or More It Runs Fine Again. I Used The Paper Clip Diagnostics A Few Times Right After It Starts Happening & It Doesn't Show Me Any Codes Besides # 12 & Someone Plugged In An OBD1 Scanner But Still Nothing Came Up. Can Someone Please Help? Thanks!

Vader

Idle sloppy? As in an erratic idle RPM, or as in misfire/shaking at idle?

Black88Z

You need to take the computer with you while you drive and make it do it again (drive stop and go for a while). This will show you exactly what the computer is seeing and will show you whats wrong and point you in the right direction, and IMO, probably is the quickest way too.

KingsHustleLA

Yes!! Nailed it lol the car gets really shaky and when i press the gas it starts misfiring & runs really sloppy/shaky, then when i let go of the gas it turns off. It fires right back up but then it gets sloppy/shaky & just turns off a few seconds later. Then I have to park & let It sit for 45+ minutes with the hood open & it will run fine again then.

KingsHustleLA

So i would need to take it to someone who does street tunes then? I don't have any electronics like that :/ What's an IMO? Sorry if that's a dumb question haha

ibmtech

iTrader: (1)

That could be a variation of problems. But I would look at the IACV in particular. You can remove it from your throttle body and ensure that it isn't all corroded at the end. With the engine cool, remove it from the Thottle body and hook up the 4 prong connector. Turn the key to on position and you should see the plunger move.. It doesn't move very far but it is noticable. The IACV (Idle Air Control Valve) is what is used to keep it going when the car is at idle along with many other things.. But it is a place to start.

KingsHustleLA

Ok it's cool right now so i'll go ahead and pull that off, should i spray it with MAF sensor cleaner as well why it's out? Also if that messes up the obd1 scanner or check engine light diagnostics misses that too? Just wondering that question for a possible future reference. I like to learn everything lol

KingsHustleLA

Oh you know what, the IACV sensor along with the coolant sensor just got replaced about 2 months ago, unless it could have messed up again?

ibmtech

iTrader: (1)

I can't remember the numbers for the IACV when looking at a computer screen.. I think it goes to 255 when full open and drops to 0-25 when running... That is what another user was talking about when running a computer... That would show you the numbers I was talking about.. Any Laptop running Win95 or newer , Tunerpro software which is free and a ALDL cable with a USB connector and your are set..

Black88Z

IMO stands for In My Opinion lol

If the IACV and coolant temp sens. were just replaced, I would say its safe to rule them out. Unless they were damaged/defective parts or installed wrong. Did the problem happen immediatly after or shortly after? Was the IACV set properly? I believe there is a process in which you have to set it for minimum idle, but I may be wrong.

Have you checked fuel pressure? I think thats what Id check next.

As mentioned already, if you have access to a laptop with windows95 or newer you can download Tunerpro and hook it up to the car, then take it for a drive. Watch the computer (and the road! lol) and you will see in Realtime what your cars computer is seeing, and when the problem arises you will see which sensor is causing the problem. It may not be a sensor though, it may be an issue such as fuel pressure. My car did a very similar thing and it turned out my fuel pressure was ok (still a little low) when the engine was cold (running rich) but when it was warming up it would drop off the cliff, causing a horrible idle, stumbling and misfiring, and eventually stalling. It ran good cold though, which was what was a bit misleading. I highly recommend looking into this if you havent already.

ibmtech

iTrader: (1)

There isn't any real adjustment for the IACV.. Since it is just a stepper motor that goes in and out it, can't be adjusted. Probably the worst thing I have see people do is great the end and try to push or pull it in or out.. There is a posibility of it being bad..

Something else I have done.

Get the car running and unplug the IACV so it stays in 1 position.. Then try to drive the car and see if there is any change with your problem. It shouldn't kick off the SES light or I have never seen it kick off the SES light as it isn't a sensor, it is a stepper motor.

KingsHustleLA

Oh ok so i could just download & install the software & get one of those cables then I could check & learn how to do computer tunes myself? Also the ALDL cable, can i buy one of those from eBay or something?

KingsHustleLA

Ohhhhh IMO=in my opinion LoL I was stuck on car mode that slipped my mind. well honestly about 3 months ago my car would start and run for literally a minute then the idle would get sloppy/shaky & die, i couldn't figure it out so i took it to a shop & they replaced those 2 sensors & that didn't fix my problem so i took it back, they had it for 2 weeks so i got pissed off and called to go get my car back & my money and 2 Hours i get a call back saying its fixed, it seemed ok until about a month after it started doing what it does now. the guy said it was a wire that was shorting out, he never showed it to me but i was so pissed i just took my car and left before i kicked his *** lol anyway yeah i've never looked into the whole hooking it up to a computer thing but now i'm about to look into it lol hmm yeah i heard it might be the fuel pressure but my car seems like it runs richer than usual & also burns more gas than usual plus i just swapped in a walbro 255lph fuel pump a little over a year ago so i have completely neglected that part but maybe i should look into how much fuel pressure i'm getting anyway just to check it off the list

Another thing i might add, my car is lacking performance even before it the idle starts getting sloppy/shaky & dies. Maybe that may help point out the problem?

ibmtech

iTrader: (1)

I would look at a site called

http://www.moates.net/shop-by-vehicl...-pre-1996.html

CABL1 OBD1-Style ALDL Connector
$30.00

Download the Tunerpro software and you are all set.

KingsHustleLA

Ok should i drive the car around a little first before unplugging it or just let it warm up for a few minutes then unplug it and drive it around? also after i plug the IACV will i notice any instant changes or should it just feel the same or exactly what should i pay attention for? just so i can know exactly what to look for and not get confused then end up not figuring the right thing out lol

KingsHustleLA

Ok this is the one i need right?

http://www.moates.net/cabl1-obd1-sty...connector.html

Also the other end looks like it plugs into a phone jack, does that plug into where the internet cable is supposed to plug in or is it supposed to be a USB plug?

ibmtech

iTrader: (1)

Here is a good one... Don't use that last one that I previously listed at it is for use with the autoprom APU1

http://www.aldlcable.com/sc/details.asp?item=aldlobd1u

Black88Z

This is a very good idea, Id definetly give this a shot. This and test fuel pressure, while waiting for that cable to come in the mail lol. Its hard for me to believe that 1 cable can cost $60 though!!

KingsHustleLA

Alright thanks! Daem $60!? i'm going to look on eBay 1st real quick lol

ASE doc

The symptom you describe sounds more to me like a heat related failure of the ICM, pick up coil, or injectors than an IAC issue. Certainly don't overlook the IAC but be aware that the ICM and/or pick up coil(in the distrbutor) are common causes of heat related drivability problems, also, I see alot of heat related injector issues as well.

To check the injectors, test them for resistance at each injector coil, both hot and cold. Minumum resistance is about 12ohms. If one or more are much lower than this, remove them and send them in for testing and service by an injector service shop.

The ICM can be tested by many auto parts stores but when they are suffering heat related failure, they generally pass the cold bench test. Best to replace it if it's suspect. And use a good part like AC Delco or NAPA Premium brand(made by Standard Motor Products). The pick up coil can be tested for resistance. It should read between 800- 1000 ohms. Test between the green and white wires that plug into the back of the ICM, with them unplugged.

KingsHustleLA

Yeah my car get's to about 220 when it starts acting up like that, it usually doesn't get far passed the 1st line then it goes right back down to it. ok so i'll check the injectors, the ICM i just swapped out like 2 months ago, I'm not sure if it could have messed up again already but i'll go ahead and have autozone check that. The pickup coil is like what $12-$15? Maybe i should just change that anyways, if it isn't the problem now at least i'll be avoiding that as a problem in the near future.

KingsHustleLA

Oh and by checking the injectors both hot & cold does that mean to text them while the car is cold then drive around to warm the car up and check the injectors again?

ASE doc

Yes, that's what that means. It isn't easy on a TPI. An alternative is to simply remove the injectors and send them in to an injector service. They will test them on their flow bench which can read actual impedance while they run. The tests they do are much more comprehensive and thorough than a simple cold-hot ohm test. The cost is generally about $20 per injector. Or you can just buy a new set of Bosch IIIs from South Bay for about $260.

KingsHustleLA

Oh alright cool, I tested all my injectors earlier while they were hot & all of them are pretty much at 19.1 ohms (they're after market) I'm going to do the cold test in the morning. So if they all read the same ohms there can still be something wrong with them? Oh aren't those South Bay injectors the modified LS1 injectors made for TPI platform?

KingsHustleLA

For the pickup coil do i just set the voltometer to 2000 Ohms & touch the Green/white pins on the plug that attaches to the ICM?

KingsHustleLA

I just tested my pickup coil with the voltometer while cold and it gave me an 856 ohm reading, should i test it again when it's hot? Another thing is my injectors are only like 3 1/2 years old and i've always used good gas either shell or 76 91 octane & they all tested good around 19.1 when hot.

tinymenace

Wondering if you figured anything out. on my 89 350tpi after 45min of driving it starts to run rough and stalls like its flooding or out of gas. If I let it cool down can run it again for awhile. In the last month I switched fuel pump and filter, sending unit, injectors, iac, tps, distributer, plugs, wires, set timing I'm just lost my car shows no trouble codes

TTOP350

iTrader: (8)

I would also look at the ign coil performance while its hot.

ASE doc

Good point.

850ohms is on the low side for the pick up coil. Do test it again hot.

One thing that is common practice for diagnostic technicians is online testing. In other words, testing the vehicle while it runs, recreating the conditions where the trouble is most likely to occur. There is no better way to pinpoint a problem than to catch the failing part in the act of failing.

Tools that are helpful, if not necessary for this are a scan tool with data stream capability so that we can watch ECM data to look for a fueling or sensor issue, long test leads so that we can monitor crank reference on a DVOM to look for the pick up coil or ICM dropping out. The crank reference pulse is a 5 volt digital signal(square wave) that runs on the purple/white wire of the four pin ICM connector. It will look like 2.5 volts on a DVOM. 0 volts or 5 volts would mean the signal is lost. A lab scope is even better as it lets us see the actual waveform.

tinymenace

Fixed my problem. New computer and BAM just like new again.