ISC Issues

[chrisfullwood]

I just recently put a replacement ISC in my car, as it was stumbling, would die at stop signs, idled horribly. i tested it before i put it in and it was 34.5 across the board for each set of pins.
just took it off and tested it. 39.5-40.0 on each set of pins. and the car has begun doing the same stuff. any ideas?
i checked my plugs and they are all white, so im thinking i neec to swap to the others, i currently am running NGK BP7ES, with NGK 8.5 mm plug wires.

 

[The_EE]

Are you sure you have no boost leaks? Check that. Also, did you replace the o-ring for the ISC? If you are using the original it could be bad and not sealing which would cause a boost leak.

 

[BISHILVR]

Your isc numbers look fine, its not shorted or burned out. I would have to say that you have a problem elsewhere, as in a boost leak or a bad ecu, etc. Stumbling or stalling issues can be many things. A few tests by you would do us alot of good in diagnosis recomendations. Boost leak test, fuel pressure test, and compression test would be a big plus for us if you can get those or even a few of those it would be better than nothing. Do you have access to a data logger?

 

[steve]

What were the readings from the old ISC?

Quite a few of the ECUs that show up here have bad ISC circuits. Only a small number of them are burnt up drivers where you can see the damage.

What does your logger read for ISC steps. When you first turn on the ignition it will read 100+ then quickly after you start a cold car it will go to 0 and as the car warms up an the FIAV closes it should be about 10-20 at idle and increase with RPM when your driving.

The ECU doesn't try and use the ISC for idle control unless the IPS is closed.

Steve

 

[chrisfullwood]

im going to try answering the last 3 posts worth of questions.
i can do a compression test, ill try it tonight if its not too cold (just got over a cold, dont want to get sicker) i just replaced the headgasket, and the numbers then were approx, 145, 145, 125, 125. that was right after the gasket swap, so the engine block was dry (before running it after the gasket swap.
the isc numbers on the old one were, 1-2 - 29, 2-3 - Zero, 4-5 - zero, 5-6 29.
when i say zero, on my tester it showes O.L (i believe its that, working off memory) basically it doesnt show anything at all. not even 0.01
boost leak, i dont have a tank or compressor that is working at the minute. there could be a few small ones. which i would have to check, and as for the isc o-ring, it is possible, i dont have one. ill have to source one this evening.
as for the logger, i just got a palm 3c in the mail yesterday, plugged it in and nothing. the red light came on to charge for a minute, then faded out. and the back of the palm got really hot.....so im working with the seller (on ebay) to get it fixed, im trying another a.c adapter, as now the adapter doesnt get warm...so long story....i brought it to try to diagnose these problems....
whats funny is that it is completely random, when the car is cold its ok for a few minutes, after a few minutes it starts missfiring and stumbling. im going to put new plugs in it tonight. even though my old ones have only 2600 miles on it.
im almost wondering if there isnt a leak around the injectors. as my 550ccs didnt fit with the stock isolator things. so i removed them, and bolted it in, they seems to fit fine and snug...anyone else have this issue? it hasnt caused a problem since the headgasket went.

long i know, but hopefully covers everyones questions.

 

[steve]

the isc numbers on the old one were, 1-2 - 29, 2-3 - Zero, 4-5 - zero, 5-6 29.
when i say zero, on my tester it showes O.L (i believe its that, working off memory) basically it doesnt show anything at all. not even 0.01

boost leak, i dont have a tank or compressor that is working at the minute. there could be a few small ones. which i would have to check, and as for the isc o-ring, it is possible, i dont have one. ill have to source one this evening.

im almost wondering if there isnt a leak around the injectors. as my 550ccs didnt fit with the stock isolator things. so i removed them, and bolted it in, they seems to fit fine and snug.

Zero is what the meter reads when you touch the two probes together. Infinity is what it reads when the two aren't touching. The first case is also called shorted and the second open.
True readings of zero then indicate a shorted winding that will fry the driver on the ECU board (also happens if the coil reads < 10 ohms), opens don't cause any problem other than the ISC doesn't work.

The injector must have some sort of insulator around it's pintle since that seals between the injector and the head. Otherwise you have a huge vacuum/boost leak.

Steve

 

[chrisfullwood]

where would i be able to get the insulators for the injectors? and i tried using the insulator thingys, and the fuel rail doesnt bolt to the head if i use them. it is possible i am missing a part hear somewhere, as i had to buy the fuel rail and the head seperately. (brought the car with the engine pretty well trashed, and alot of parts missing. so if im missing something here, please feel free to tell me.
thanks
Chris
oh, where can i get an o-ring that will fit the isc, as i have a sneaky feeling there isnt one on the new isc i put on, and i dont recall there being one on the old one either?

UPDATE **i just remember i have covered the isc hole with sealant as a test to see if it was leaking....it didnt make a difference.

 

[steve]

where would i be able to get the insulators for the injectors?

oh, where can i get an o-ring that will fit the isc, as i have a sneaky feeling there isnt one on the new isc i put on, and i dont recall there being one on the old one either?

Which insulators you use depends on which brand of injectors. Almost everything used the factory style insulator except various versions of the Rochester/FIC/PTE injectors.

You do have the black spacers for the fuel rail, right?

The o-ring goes into the throttle body and seals between it and the ISC. Dealership is the only place I've found for it.

Steve

 

[talontsi18]

Your probally going to have to get the oring from the dealer or try to go match one at a parts store. You have to have the black rubber insulators that hold the injector into the port in the head. If you don't have these in you have a big leak there no matter what. Do you have the black plastic spacers in place between the head and the fuel rail? They go where each mouting point is(3 total). Make sure your injectors are they right ones for the car as well.

 

[talontsi18]

Steve your just to fast on the draw. Steve I also sent you a PM last week and I have never gotten a reply. It was about an ecu being socketed.

 

[steve]

I don't have your PM.
email is the better way to reach me.

 

[BISHILVR]

A boost leak test will tell the story if you can get one for us. Just let us know when you do that.

 

[chrisfullwood]

i think im missing the isolators for the injectors. i have the ones for the fuel rail but not for the injectors. (i have to admit that would be from inexperience with dsm's(galants) this is the first one ive ever worked on, and no other car ive ever worked on had those, it was just o-rings that plugged into the slot in the head.

i got them used i was told they were for a 4G63 engine. they are R/C 550's

i just drove the car...it ran fine... how awesome is that. it attempted to stumble a couple of times, but you wouldn't notice unless you were waiting for it to happen.
and it died twice. this is what confuses the heck out of me, one trip the car is fine, another then it runs like crap. the time after that, it runs fine.....its so odd. (hence the logger i was trying to get)

 

[doggo]

Your probally going to have to get the oring from the dealer or try to go match one at a parts store. You have to have the black rubber insulators that hold the injector into the port in the head. If you don't have these in you have a big leak there no matter what. Do you have the black plastic spacers in place between the head and the fuel rail? They go where each mouting point is(3 total). Make sure your injectors are they right ones for the car as well.

You can't match one at the store if you don't have one to compare to. You can get one online. Try the usual sources.

 

[talontsi18]

You can't match one at the store if you don't have one to compare to. You can get one online. Try the usual sources.

Thats why I said that he will probally have to go to the dealer. If he didn't have one to compare he could take the isc to the store and try to find a o-ring to fit the spot on the ISC. Think out of the box man.

 

[calreef18]

Also see what your idle is set at, I got a isc malfunction when I messed with the idle and had it set too high. Fixed the idle and the problem went away.

 

[chrisfullwood]

when the car is running normally (not screwing up) the idle is at 750, almost spot on, it will occasionally cycle up to 780-790. but it is right on the money.

there is an o-ring on the idle set screw. it looks in good shape.

i know of one thing, that i just learnt (first time working with dsms...thats my story, i wasnt aware that the injectors are supposed to have insulators / isolators....my car didnt come with injectors or a fuel rail, so i had to get them afterwards.
it had the spacers for the fuel rail, i figured they went there, but when i went to put the injectors in, of course they didnt fit, so i removed them, and everything seemed fine. well i suspect this is a huge part of the problem.
does anyone know where i can get these isolator things?

thanks
Chris

 

[steve]

So you can see where the parts go on the injector;

You must be logged in to view this image or video.

The OEM part numbers from the dealer are (Prices are from the last time I looked):

MD614813 o-ring $2.68 each list
MD614805 sheet $4.25 each list
MD087060 insulator $1.53 each list

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You can get these from your local dealership, from JNZ, Road Race, MachV, etc.
The insulator fits into the head, the sheet between the injector and fuel rail, and the o-ring inside the rail.

Steve

 

[chrisfullwood]

thank you, this is exactly what im looking for, and im pretty sure this is going to have a lot to do with the problem. although i still think there is another issue somewhere, i just cant pin where / what it is...and i probably wont be able to until i get this stupid palm i brought working (brought it specifically for a logger....and it didnt work when i got it awesome huh.

thanks again. i hope i can inturn help someone as you have helped me.

 

[chrisfullwood]

an interesting update.....
i've had a problem with squeeling belts lately...since the headgasket went and i had to replace the isc...
so i tightened it up again, wondering why it kept coming loose. well the bottom bracket bolt was missing. so i watched the voltage on my turbo timer, and it was at like 11.2 ish.
anytime the car was running bad, thats where it was, when it ran fine it was 12.4 minimum, which begged the question. has low running voltage caused the problem, of the car running rough misfiring.
i believe yes. i open the idea to the forum?

 

[BISHILVR]

I've had that happen. Injector output can be affected by low voltage.

 

[chrisfullwood]

thats kinda what i was thinking.....cause it gets worse as i add more throttle. sa the injectors are trying to add more fuel, of course they add less because there is less power going around.

 

[steve]

Almost everything is effected by low voltage. The fuel pump pushes less fuel, the coils have a weaker spark, the injectors need longer to open, etc. Somewhere under 10v the the car really starts bogging and the ECU will shutdown somewhere around 8-9v.

When my last alternator died there was no indication it was bad until the radio and SAFC turned off and the car start bogging. I quickly checked the logger and it said 8.5v right as the engine quit. Thanks to the Optima red top and the used car lot I died in front of, I was able to get enough of a charge in 30 mins to make it home from the middle of nowhere just off the battery.

Steve

 

[BISHILVR]

You've never really experienced dsm misery until you hear the "radio click of death". Its similar to a machine gun, which is fitting. Then you start walking.

 

[chrisfullwood]

well i got my slipping alternator belts fixed. the pivot bolt that goes on the bottom of the alternator was gone....so i made a new one (didnt have anyway of getting on that long) no problem fired up, 14 volts according to my turbo timer....
drove the car, fine for a few minutes, then it started stumbling again. (pretty sure its the injector isolator thingys) i have to hope thats what it is. although im still not convinced, because a vacuum leak would cause the problem continiously where as this is random. i can drive it once, and it run horribly, then a few hours later, drive it and it would be fine. so its very odd, the isc tests fine, i have to find another palm, cause the one i got is no good. i tried using the tunerstien stuff on my laptop but it is a nightmare to try to use. and the car dies...so i cant really keep the car running and mess with the software at the same time.

i went about 2 blocks, onto the main road, up to a stop light, bamm the brakes went out. so i limped the car home (limped being the exact word to use) up the driveway. and the rear passenger side brake line was worn thru. some idiot put the wrong brake caliper on the back, it sticks out and then the line has to bend 90 degrees to make it out from the wheel, where as all the other are 45 degrees. so another thing to contend with.
anyone got a spare rear wheel caliper they dont need?