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Discussion Starter · #1 ·
Hi, I dragged the old 99 Vitara 1.6 out for the first time in a while and it was idling at 2.5 k and missfiring up to about 3k. I have checked the TPS and adjusted it and it now idles at 800rpm but still sounds a little lumpy. Any ideas? Its the carb model and its done 70k owned by me since new so its been looked after. Thank you
 

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Are you located in the UK? We have a number of posters here who are familiar with the UK models (and carbs). I am not, but off the top of my head I would wonder if after sitting for such a period of time that the carb, jets, needle, etc would not need to be cleaned first, prior to adjusting your throttle position sensor. Normally, it is a good idea to make sure the mechanical systems are operating as they should, before making adjustments.....The least I can say is to also check your spark plugs to see the condition of the tips - not wet, black, white, etc., and presumably they are gapped to .07mm like the EFI system.
 

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A UK model 99 Vit is throttle body injection. I would start by checking that the throttle opener is retracting, its at the back of the throttle body.
 

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Discussion Starter · #4 ·
Thank you.I am pretty sure its running rich. I have set TPS and the idle is spot on so I will change the leads, dizzy cap etc tomorrow. It sounds a lot better now.
 

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Is the Check Engine Light staying on?
 

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Discussion Starter · #7 ·
No check engine light. Just high idle that did drop to normal after a few mins. After adjusting the TPS its settled down but still sounds a little lumpy below 3k
 

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Excuse my ignorance, but I don't think you can have a ECU or electronic sensors like a TPS with a carb model.....??? Are you sure it's not the 8v throttle body?? Where is the location of your air filter - and is it round in the center of the engine or square ad off to the side??
 

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Discussion Starter · #9 ·
Its a square one next to passenger side wing. I may well be wrong but to me it looked like a Carb lol
 

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Nope. Welcome to the world of fuel injection!! I then assume that you are the 8v throttle body, as Rhino said above.
So, first confirm that your check engine light on the dash is on with the key on, and then off when the car starts. Also advise what your cold idle is, and exactly what the car does between cold and warm idle (and if the car heats up properly - you should have great heat in the cab). Basically, assuming this is the 8v, your car should start at about 2000 rpm, then within 5-10 seconds you should hear a noticeable drop of rpm to about 1500 rpm or so, and then the idle will slowly drop to a steady 800 rpm as the car warms up. You should also be able to get a code 12 from the check engine light. Instructions here:
Check Engine Light
Also confirm that your spark plugs are gapped to .07mm, and not just used out of the box. Normally, idle is a symptom, rather than a problem itself - adjusting the TPS may have helped, but it may also have masked the original problem. There is a specific way to calibrate the TPS, rather than just loosening it and turning it.
On the 8v, high idle happens when there are vacuum leaks somewhere. Take a pliers and pinch each of the vaccum lines. With the exception of the one vacuum line that runs from the air pipe at the air filter to the idle speed solenoid, you should have no change in idle with the hoses pinched. If you do, you have found a leaky circuit - hose, gasket, etc.
By the way, TPS calibration instructions here:
http://www.suzuki-forums.com/suzuki...geo-tracker/50555-tps-set-up-diagnostics.html
 

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Discussion Starter · #11 ·
Thank you, I have checked the Check Engine light and its fine, The heat is great and if I unplug the what I think us auto choke it runs perfectly with no missfire and perfect idle. I will check the vacuum pipes later. My Discovery had a vacuum issue on the wastegate actuator and after many new parts (excuse to buy for the wife) I discovered the tiny hole in the pipe.
I have taken the Suzuki for a drive and its lovely with the thingy unplugged..from what I gathered from the symptoms is the auto choke if thats what it is was sticking on causing the rich mixture smell of petrol etc. I maybe wrong but without it plugged in( electrical connection plug just above the TPS its running really nicely.
I really appreciate all the kind help. I will gap the plugs later also.
 

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There is no choke on an EFI model but if you unplug a sensor then the ECU will revert to a failsafe mode, that can often disguise an issue. What exactly have you unplugged? can you post a picture?
 

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Discussion Starter · #13 ·
Hi thank you for the help. I have checked the vacuum pipes and all seems fine. When I remove the second plug lead from the front the revs hardly change. Its sparking ok and I have checked and cleaned the dizzy cap and rotor arm. I cant get the plugs out until the morning because my friend has my plug socket. Its on three and a half cylinders lol. Its way to quick to be just on three. On moving the TPS it seems to be slightly better. I have not set it with a multi tester since mine is a 50yr old Avo and not digital. Also when I try to hold a constant 2k revs in neutral it is ok for a second then it hunts badly between 1.5 and 2.5k rpm. It has improved with the TPS being adjusted. It drives lovely on high rpm. May I ask if the plug gap is crucial on these engines. I appreciate all your help. Thanks again
 

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The AVO will work well enough for the TPS adjustment. The plug gap needs to be at the factory settings, often new plugs are supplied with too big a gap.
 

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Discussion Starter · #15 ·
Hi, May I ask how I set the Avo to set the TPS and how do I set the TPS and what should the plug gap be please. Would the wrong plug gaps cause the missfire and hunting.
Thank you
 

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As already posted, the plug gaps need to be .07mm (.028") - normally they come around .044", which is too wide, so they need to be re-gapped.
Your multi-tester - which I assume uses the needle to sweep across - is actually better for testing the resistance of the TPS, as you watch the needle sweep in one direction when doing it - I use an ancient Lafayette (probably never heard of them in the UK) that is about as old as I am.
The proper way to calibrate the TPS is in the link above, already posted here. At the rear of the throttle body, by the firewall, you will find a dashpot - valve - which is actually the throttle opener on the car, and works similar to an automatic choke. The throttle opener is normally open, until the ECU comes on board and provides vacuum to it, to close it. This is why your idle noticeably should drop within 5-10 seconds of the car cold starting - this valve is closing, blocking additional air and dropping the rpms.
And yes, it's a good idea to post a photo of what you are unplugging. As Rhino explained, when you unplug any of the sensors, the computer will revert to a pre-determined set of values to keep the car running - your car would then run rich, gas (petrol) mileage will go down, etc. Post a photo of what you are unplugging - and perhaps far enough away so we can see it's location.....
 

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Discussion Starter · #17 ·
Thank you. I am unable to post pictures due to being useless with computers. I am using my phone to access this forum. The thing I unplugged is on the throttle body just above the TPS on the right hand side. I have plugged it back in and the idle seems ok starting about 2k and settling to about 800 after a few seconds. What are the symptoms of a faulty TPS? . I will gap the plugs first thing and set it up. If the TPS is set wrong can it cause the hunting and missfire?
 

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Basically, hunting is when the computer is attempting to control the idle, but continues to lose control. The foundation of your engine is mechanical - the valve timing and ignition timing must be correct before you begin to look at individual sensors - the ECU cannot control bad timing. My normal suggestion is to do a compression test on the engine to start (all spark plugs out, remove the F1 fuse which will stop fuel and spark, have a fully charged battery, and floor the throttle when cranking for the best compression). Then make sure that you ignition timing is correct, spark plugs gapped properly. Make sure the car is warming up to proper running temp (great heat is a good indication of this).

Here is a (bad) photo of what should be your engine. Point out the thing that you are disconnecting. Is it the IS??:
 

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Discussion Starter · #19 ·
Its the connector behind the ISC. I have had it connected all afternoon. It seemed to make it idle better but didnt whilst driving. Thank you
 

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Ah, ok, the connector for the ISC, yes? The idle speed solenoid basically is involved with idle, and with maintaining your idle while there is a load on the engine. You can easily check its function in a number of ways. First, you will see an air hose going from the air pipe at the air filter, to the ISC itself. Pinch that with a pliers. Your idle should drop to about 400 rpm or lower. Next, with the car properly warmed up, turn on your headlights and heater fan blower on high, creating a load on the engine. What does the idle do? The ISC is supposed to maintain the idle at whatever it was, and not allow the idle to drop down. If you have A/C (and why would this be needed in the UK...??), turn the A/C on and watch the idle - it should actually go up a couple of hundred rpms.
The ISC works off of a small plunger that vibrates about 20x a second (and has been doing so for the life of the car....). It can get dirty inside, the plunger can stick, the spring inside can wear out, etc. You can remove the ISC from the car (note that 2 of the hoses going to it are coolant hoses, and you will lose coolant when you do this). When you remove it, shake it. Does it rattle? If so, it's no good. Otherwise, you can carefully soak this in carb cleaner, and test it on the bench by connecting it to 12 vdc (a poster here once got it to work on a 9v battery like what you would have for a smoke alarm). You will (hopefully) see the plunger vibrating back and forth when it's cleaned properly. Replacement ISC's are quite expensive - so if any of the idle tests above 'fail', it's a good idea to try to clean it to get it to work properly. Also, of course - you need to check the wiring to the ISC, to make sure that the connection is secure and the wiring is good. With the key in the on position, you should have 12v going to the blue/black wire at the ISC connector, and no voltage on the light green/black wire (ground).
There, that should keep you busy for a while....;)
 
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