1G Car just dies after working completly fine

[Moovingon1GEclipse]

Hi, bit knew to this, got first DSM about 2 months ago. The car at start had a bit of a rought idle, swapped in spark plugs and before it would go to 1,000 RPM and dip to 500'ish... now hits around 1.8k and then starts to come down like normal.

But what i don't get is that sometimes the car runs completly smoothly after starting and me driving it.
The other day did around a 30mint drive stopped the car around for another 1hour and 30mint when i came back to it the RPM went up and straight back down to 0 ....
and sometimes it goes veeeryyyyy lightly back and foward when slowing down and i don't believe it's being in to much of a high gear cause it happens also around 3k RPM when slowwing on third gear for example...

Im just waiting for my day off so i can actually have time to work on the car, but im thinking in cleaning the throttle boddy, the IAC valve, and checking the MAF ( i have one extra might replace to check if it changes anything )
i believe i have a fuel system leak or air system leak ... injectors look fine ... never saw fuel dripping from it whatsoever ... so im inclined for the air system currently, so after checking the air system if nothing changes i'll probably turn myself back to the fuel system. But any advices on something else that i should check ?

kinda hard to find help here in Europe about theese cars, plus mechanics here are a completly rip off ... take the car there ... charge you a price of a new one + they brake something so you fall into the endless pit of taking your car to a mechanic....

i don't find that it's loosing any power whatsoever... i think...

 

[waltah]

Do you have a Check Engine light? Any codes? 1G doesn't give you much but you might get lucky.

Next thing I'd do is get the shop manual and study the adjustments for, and operation of the idle speed controls. There are several parts and adjustments that interact and too many cars come with everything mis-adjusted. There's a downloadable manual available via this site and eBay (and similar sources) sell the hard copy ones.

The throttle stop screw, the Basic Idle Speed Setting (BISS) screw, the closed throttle position switch, and the IAC valve in that order are the points to check. Cleaning the throttle body is never a bad idea but be careful not to get cleaner down in the large passage in the bottom of the bore -- plug that up. The IAC is down there and if the lubricant is washed out or crud flushed in you are likely to get new trouble.

This isn't likely to be a MAF problem or a fuel system problem. A good size air leak, maybe -- the ECM/TCM deals with 'too lean to have enough torque to hold idle speed' by opening the IAC which gives it even more air so it almost dies ...

Study the adjustments above, confirm that they're okay, then go from there. It's best to go slowly, and not change a bunch of things let alone start throwing parts at the problem. It may take a while to figure it out but you'll get there.

It sounds like European mechanics are much like ours here in the states. Probably half my cars (don't ask the number!) arrived here when someone gave up getting a fixable problem repaired.

 

[Moovingon1GEclipse]

Do you have a Check Engine light? Any codes? 1G doesn't give you much but you might get lucky.

Next thing I'd do is get the shop manual and study the adjustments for, and operation of the idle speed controls. There are several parts and adjustments that interact and too many cars come with everything mis-adjusted. There's a downloadable manual available via this site and eBay (and similar sources) sell the hard copy ones.

The throttle stop screw, the Basic Idle Speed Setting (BISS) screw, the closed throttle position switch, and the IAC valve in that order are the points to check. Cleaning the throttle body is never a bad idea but be careful not to get cleaner down in the large passage in the bottom of the bore -- plug that up. The IAC is down there and if the lubricant is washed out or crud flushed in you are likely to get new trouble.

This isn't likely to be a MAF problem or a fuel system problem. A good size air leak, maybe -- the ECM/TCM deals with 'too lean to have enough torque to hold idle speed' by opening the IAC which gives it even more air so it almost dies ...

Study the adjustments above, confirm that they're okay, then go from there. It's best to go slowly, and not change a bunch of things let alone start throwing parts at the problem. It may take a while to figure it out but you'll get there.

It sounds like European mechanics are much like ours here in the states. Probably half my cars (don't ask the number!) arrived here when someone gave up getting a fixable problem repaired.

Forgot to mention it, but yeah i have no Check Engine light at all.

Thank you very much for your reply and guidance in this subject. I will do that, in that order.
I wasn't planning in doing random stuff all at the same time, other wise i wouldn't even know what the problem was, or if i fixed it, or just made it worse by changing something i shouldn't, i'll do 1 thing at a time to make sure i don't overdo it and mess something up...

Besides that the car runs great... it has only 156k KM's around 96k miles and it's in fairly good shape just needs some love and i wanna make sure it's healthy before i take care of the asthetic of the car. Why have a pretty car that doesn't run properly right ?

Well, thank you very much and i'll give some updates next week after i work on it over the weekend. I will also be changing the belts since they are pretty dry, water pump etc... over the weekend if the material arrives on time for it.

 

[waltah]

Maybe I should stop reading DSMT? Maybe this stuff is contagious?

Yesterday my wife was going to take a 5-hour round trip in her Expo LRV. '94. very much like the 1G DSMs, has a 4g64 engine. Started car, okay, five minutes of warmup while she loaded final stuff up and all of a sudden the idle RPM is going up to maybe 2000 then back down to 500 or so, then back up ... with a period of a couple of seconds.

Huh. First question is: Is the ISC doing this? So I unplugged it -- the 6 pin connector on the lower firewall side of the ISC. Made NO difference -- idle speed still going way up, way down, way up ...

So somebody -- is supplying way too much air, revs go too high, CPU says "This is not good" and shuts off fuel ... rinse, repeat. Yesterday afternoon I replaced the ISC with a new one -- trouble gone. She took the trip today and has had no problems.

I disassembled the bad ISC and it was indeed at 'full open.' On a warm day that would be a wow, mighty fast idle. It was not stuck -- everything moved freely -- but I have not yet checked the motor.

You might try that test -- when the car is idling up and down, unplug the ISC. If that doesn't change things you've found the villain. Yours may mostly just be sticky rather than 'stopped cold' as this would cause speed variation when coasting foot off the throttle. The ISC takes over when you do that to keep the throttle from slamming shut and causing the engine to die at a stop sign. ('Dashpot function') but it is supposed to allow it to slow gradually to a normal idle.

The ISC can be disassembled, cleaned and lubed but I've had only moderate success doing that. Might be worth a try -- remove the assembly from the TB, working on a large light color towel or something like that take off the 2 bolts holding the cover and remove it. There's a spring or two in there and while it won't shoot anything across the room, the insides will fall out and the parts are small. You have to take out the itty-bitty Philips head screw in there to remove the valve pintle which is the part that's most likely to need lube. A lightweight 'instrument' grease or something like that.

Loss of grease often happens when the TB is cleaned with carb cleaner but the hole in the bottom of the bore that goes down to the ISC isn't plugged and the solvent washes the grease away.

Sometimes the insides bust up -- usually the lug on the pintle and that can jam things. Anything broken, it's trash. Assembly is kind of confusing but the parts will only go together one way.

I've had good results with the Taiwan-made ISC assemblies on eBay but do study part numbers and be suspicious of those that say they cover several Mitsu p/n's as they may not cover them all properly. The ISC is a needle valve that's calibrated to supply the right amount of air for fast idle on a particular engine: If it's the wrong size then you may not have a fast enough fast idle in very cold weather.

The OEM parts suppliers say they still have them but $US 340 or something like that. Taiwan $80 and quite beautifully made.