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Discussion Starter · #1 ·
Hello all,

97 Tracker 16v Manual Transmission 4wd.

I bought it and installed a new thermostat and new spark plugs. It ran great but always idled a little high. On occasion it would idle down to roughly 1200 which is still high but I didnt want to mess with it. Now in the winter it will start and idle at roughly 2500 rpm and will not come down much untill warm where it will idle between 1500 and 2000 rpm, while still occasionally only dropping to roughly 1200. Just recently as of yesterday, it began to to have a surging idle and now on initial startup it idles at 3000+ rpm.

I have read many threads on here and page after page of idle symptoms and I believe it is related to either an air pocket in the cooling system or a bad IAC. Also, it has a p0505 code. It had the p0505 before when it was starting at 2500 rpm and steadily idling at 1500.

My question is am I in the ball park? Does anyone have any thoughts/ comments/ questions/ advice/ tips/ tricks?

Tomorrow I intend on taking the ISC off and doing the shake test to see if there is a rattle which would tend to a bad ISC/IAC.. correct?

Should I calibrate the idle switch to the TPS?

I am lost and do not know where to start. Any help will be appreciated, thanks in advance.
 

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Idle is a symptom of a problem, and not the problem itself. Personally, as this car is fairly new to you, I would start with a compression test to make sure that the engine is timed properly, and then verify the ignition timing, before I started fiddling with anything else. You need the foundation of good timing in order to diagnose anything.
Normally, your car should start up at about 1500-2000 rpm at cold start, and then just slowly decrease as the engine warms up, to a steady 800 rpm warm idle.
P0505 is a 'IAC system malfunction'. The terms IAC and ISC is somewhat confusing with Suzuki, but in the p0505 it is actually for the idle speed solenoid which you can find if you follow the vacuum hose that comes off the air pipe by the air filter, and goes to the solenoid. If you pinch that hose with a pliers, stopping air to the solenoid, your idle should drop considerably. If it doesn't, then you have an air leak, and the ECU cannot control idle with so much extra air. The ISC can also be removed from the car, and tested with 12vdc - there is a small plunger inside that vibrates at 20x a second, that can get clogged with carbon, etc. You can clean this with carb cleaner, so that the plunger can freely vibrate.
 

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Discussion Starter · #3 ·
This morning I unplugged the IAC/ISC and all symptoms went away. It started and came up to about 2000 rpm. Slowly dropped down to about 1000 rpm. The temperature here is in the negatives.


Yesterday I unplugged the maf because I couldn't deal with the 3500 rpm idle. It of course ran like crap and didn't want to idle after unplugging the maf but at least I was able to drive it without it doing what it wanted. The afore mentioned IAC unplug was with the maf plugged in.

I intend on removing the IAC tonight for cleaning and reinstalling. Will post results.

Please advise whether or not I am in the right track. Thank you
 

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By unplugging the MAF, you force the computer to use a pre-set table of values, rather than using information from the sensor, so that the car, while running, will run rich with less power. However, if you unplug the ISC, it should the car should do exactly what it did, idle should drop really low or car should stall. This is similar to if you had left the ISC connected, and just pinched the air hose closed that goes to it - the idle should also drop. So this would seem to show that the ISC is working as it should. But it may be a good idea to clean it anyway, to make sure that it's not sticking and the plunger can work freely. While p0505 states IAC malfunction, it really means that the computer cannot control the idle. And reasons for that can be air leaks, sticking EGR, TPS not calibrated correctly so that the idle switch is not closing, etc.
 

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Discussion Starter · #5 ·
So as of yesterday, I removed the IAC and found it to have some carbon build up on te plunger inside. I cleaned it out with carb cleaner and cycled the valve using my power probe. It cycled quickly without a hitch and I shook it and didn t hear anything inside so I reinstalled the IAC. I restarted the vehicle and all the symptoms went away. At operating temperature the idle went down to about 1000. I looked at the distributor and saw a mark on it, previously I had wondered if someone cranked the timing so using my scanner I found base timing at 1000 to be roughly 10* advanced. I retarded the timing and the idle set down to 750/800 rpm. Rev it up and it fell back to about 1500 where it caught itself and and came back to 750/800. Awesome!

Upon driving home, I noticed it seemed to not be as snappy and slightly sluggish up to 3000 rpm.

Today I put te distributor back to where it was previous and drove it again and it is more responsive and revs faster/ harder. It now idles when hot about 1000 rpm though( according to the tach not the scanner, I noticed there was a difference between the two numbers when I had the scanner on.

What can I fine time to bring the idle down again just a touch. Also since I've had the vehicle I noticed in first or second gesr at sustained rpm of about 2/3k the throttle cuts itself out. Then comes back. Do I need to reset tps?

As far as I'm concerned, I'm happy with how the vehicle operates now. It's never idled better and it's obviously worlds better than the surhing and ridiculous high idle of before. Thanks for all the help!
 

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Glad things are getting better. It may be a good idea to start from the beginning with the ignition timing - assuming that the engine timing is good - and retime the ignition, also making sure that your plugs are gapped to .028". Sometimes, a bit of high idle can be because of a vacuum leak - particularly as hoses and gaskets are starting to age. You can do somewhat of a test by pinching the vacuum hoses with a pliers to see if any of them cause the idle to change. Only the ISC hose should change (drop considerably) the idle - all other hoses shouldn't cause a change. If they do, then there is a vacuum leak on that circuit. Well done with the ISC cleaning! I would test for vacuum leaks though, before going through a TPS calibration.
 

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Discussion Starter · #7 ·
Forgot to mention, after I cleaned the ISC and got everything back together and running, I did pinch the vaccuum hoses and spray all lines/ throttle body/ intake plenum/ air intake/ egr tube with brake clean. No idle changes. Of course I could probably try again with propane and do it a little more precisely. I will do the pinch test again to double check next I have time.

Also I noticed some coolant on the ground the other day. On the back of the head where the coolant is exhausted to the heater core, is that known to leak? Could a small leak confuse the coolant temp sensor by trapping air due to expansion/ condensing of cooling system. Also heat in the car is above "warm" but not quite "hot". I'm thinking this is due to loss of coolant pressure.. which would lower the coolant temp. it also takes a while to warm up fully. But it's hard since it's been negatives to positive teens outside for the past month or more. I will pressure test next time I have time as well and stick a thermometer in the vents to post better figures.
 

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I don't think that such a small coolant leak (and small enough where you have not even noticed that your coolant level is changing) would make much of a difference. Hoses can be an issue on an old car - I would expect it would be a good idea to change the coolant hose going to the heater core, as they tend to deteriorate, especially where they meet the metal pipe. Getting an IR thermometer would give you a good indication as to engine temp.
 

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Discussion Starter · #9 ·
**UPDATE**

After a few days and a few drive cycles with the IAC/ISC unplugged the tracker would cold start about 2000 rpm, settle down to 1500 after maybe 20/30 seconds. Then stay there untill the temp guage came up to C and begin going down to about 1000. I began pinching lines off one by one in various places, taking my time, boom! Line from evap canister purge solenoid is open.. pinch it off, warm idle drops (by ear) a couple hundred rpms. Closer inspection of hose from solenoid to port on intake reveals a cut in the line.. maybe from me pinching it off? I replaced the hose with some orange line I had, which helped. Then I pinched off the line before the solenoid and idle dropped again. That says that the purge solenoid is stuck open.. not only creating a vaccuum leak, but also potentially flowing HC's which helped to mess up A/F ratio at idle and confuse pcm?

I have since simply put a rubber cap on the port at the intake. From there I fine tuned the idle with the screw on top by the TPS. Currently I have it out less than 1 full turn from bottomed out.

Previously, before I messed with this screw it was roughly two turns out. Now with the IAC/ISC unplugged, EVAP Purge port blocked off, it starts at 1800/2000 rpm. Sits down to 1500 after roughly 20 seconds or so, then as it warms up comes down to about 800 which is where I set it according to my scanner. With the vehicle operating seemingly normal, and consistently, I plugged the IAC/ISC back in (while warm and idling at 800) and the idle went up to roughly 1500 rpm or so then came down to 800 where it was. Only problem is the idle now rolls slowly between 700 and 1000 rpm. I only had it plugged in while hot so I dont know what it does now after all my tinkering when cold or at start up.

With it unplugged the tracker runs great and does just what its supposed to. I currently have the IAC/ISC unplugged with the fast idle screw turned out roughly 1 turn from bottomed out. If I close this screw completely, the engine dies. Also, with the IAC/ISC plugged in and pinching the air feed line after the filter, the idle hardly changes. All this leads me to believe once again that the IAC is junk or needs a bath in an ultra sonic tank to really clean it out.

All of this rigging is to get through winter and will be fixed when the weather is nice. My question is how many turns is the fast idle screw usually out? And is that what the screw is called?

Any other ideas/ comments/ advice/ thoughts or info about the IAC/ISC diag and what i should do next about it would be appreciated. I think I have this issue figured out for the most part, but again, maybe I am missing something or could do something better. Please advise.





All this info is over the course of about a week so please excuse the rough numbers and round about diagnostics.
 

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Discussion Starter · #10 ·
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The purge solenoid on the right with the orange tubing is what i capped off at the intake.

The solenoid to the left of that controls idle as well by vacuum to a mechanical device? Im not quite sure on that, correct me if Im wrong.

Thanks
 

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I believe that this screw is called the idle speed screw, but you really should only adjust it when you are sure that all other systems are correct - such as your timing, your TPS calibration, your MAF, etc., etc. Adjusting it to 'cover up' a problem, while it will give you 800 rpm presumably, doesn't correct the problem.
When you disconnect the ISC, you are forcing the car to run lean - so pulling this and having 800 rpm doesn't indicate that the ISC is causing the problem, but that perhaps you have an idle problem elsewhere that is being rectified by forcing the car lean. Normally, if the ISC does not rattle, and you have cleaned it and made sure that the plunger is vibrating and it is not stuck open, etc., it should not be bad.
The fact that when you pinch the ISC hose with the ISC connected, and your idle does not drop (as it should) indicates that there is a problem somewhere. With the ISC connected, your EVAP hose repaired, etc., you may want to try to tap on the MAF to see if that changes your idle at all. The MAF can best tested electrically - with the key on, you can backprobe the blue/black wire to ground to confirm that you are getting battery voltage. The black wire backprobed to ground should give 0.5 volts or less. The grey wire is the output pin, and with key on, backprobed to ground, should give 1.0-1.6 volts. Then with the car started, it should give about 1.7-2.0v at 800 rpm idle. The voltage on the MAF will increase with idle speed, so if you race the engine, you should see the voltage in the MAF increase to 3v or more.
Again, ALL of this relies on your car being properly timed and tuned.
 

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Discussion Starter · #12 ·
I agree that something is up elsewhere and contributing to the symptoms I have. That is obvious.. Not all sensors are plugged in and it runs fine but only after adjustments were made. I did notice on my scanner that the intake air temp seems to be reading high or is biased. For the past 3 months it hasn't really reached temperatures more than 32*F outside. The IAT reads 50 usually and yesterday while the engine was warm and outside temperatures of about 30*F the IAT was reading 64*F. I don't know if that's normal or not or how much the good being closed matters but yesterday when the IAT read 64* the good was open letting obviously cold air directly in. Could that affect it?

I have tapped on the maf housing lightly before I'm not sure it helped. My long term fuel trims are at 10.5 right now which isn't terribly high but it's obviously richening the fuel.

When I have time I will back probe the maf and see it's readings. Along with your advice I also have a wsm to consult. I'll dig into it a little deeper and see what I come up with. Thanks
 

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The IAT can be tested with ohms - normally, as the intake temp increases the resistance in the IAT drops. With intake air at 32F, the resistance should be about 6600 ohms. With car at proper running temp, the reading should be about 350 ohms. You can test it with an ohm meter in a pan of water by heating the water and seeing if the ohms change.
 
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