Rough Idle and Electrical Problems.. HELP!

[TS87FC3S]

OK so i bought this car a couple weeks ago its an 88 GXL, it needed a clutch, so i put a stage 3 race clutch (came with it) in and when i went to drive it.. after having to be jumped it starts and wont idle right it surges, idles rough, sound like it randomly misses and cuts out. After taking it down the road anything over 1/2 throttle cut out bad till it got a lil warmer then i went to run it up in the rpms :driving: and about 6 grand it lost power, tach cut out. also car keeps dieing everytime i try to stop it dies and has to be jumped even thoughs volts show 12volts.

Any ideas? this is driving me crazy :banghead:

[Angelwankel]

Have you tried checking your AFM? TPS? CAS? Is it stock? A car that old people may have done all kinds of stuff to it, or there could be corrosion. I recomend the FSM and a bit of searching whether googling, or searching these forums or other rotary forums.

Maybe it sounds totally different, but it surges, idles rough, sounds like it randomly misses and cuts out... my car has a vacuum leak and it does what I call galloping whenever it's warmed up - but not the warm up cycle, I take it off of that - which I can imagine may be described as surging. It revs itself from anywhere between 600rpm-1100rpm, sometimes less as in 700-900rpm, while it does this, when it revs itself back down it sounds like its missing and cutting out, but that might my exhaust leak making that noise or maybe I can really hear it because of my exhaust leak. I don't know, I've never had an exhaust w/out a leak. Anyways, I was wondering if if is still stock, I took some emissions off of my car and we had to fiddle with the tps and the crank angle sensor just so my car will run, and that's without having my power steering hooked up, otherwise we may have had to have advanced the crank angle sensor a bit more.

[TS87FC3S]

it is stock, and i have cleaned the afm and it opens easy but havent been able to check it or the tps electrically, but what would cause the tach problem?

would fuel filter cause this? the inlet for fuel is pretty rusted who knows what inside looks like (previous owner didnt have a gas cap on it)

also i cleaned he intake and all piping cuz previous owner had everything coated with aiir filter oil.

[Angelwankel]

Download an FSM if you havn't already and find yourself a working multimeter and go ahead and give that amf a test. The tach problem I'm really not sure of. The car dieing when you come to a stop reminds me of when my car would die when put into reverse, and though there were 12v, it just wasn't working. If you don't find any answers or anyone else can give you some useful info I'll get a hold of my ex and see what he found wrong with my electrical gremlins that was causing my car to die like yours.

[Angelwankel]

I got a chance to chat with him. Don't want to misinterpret anything, so I just changed our names :P Here is the conversation.

Him: It was the main power wire for everything interior.There's a black connector about 3-5 inches from the main fuse box under the hood. I cut that connector out and soldered the bare wires together.
Me: it was just corrosion right?
Him: That's what caused it, but it was so bad that it was just going to keep happening...so I cut the connector out.
Me: okay. To test it, to see if that was it, did you just wiggle it a bit?
Him: Don't quote me on this, but I think the brakelights are on a different circuit..same as headlights...so his problem is different.
Him: yes I'm about 75% sure it's a different circuit...sorry. :-/:-/ Worth a shot to check it though.

[XaulZan]

Sounds like a dirty fuel issue to me, have you drained your tank and looked at the fuel, water or contaminates in the fuel will cause exactly what you describe, and if there was no gas cap on it then you could have water AND rust inside your tank, bad combo. I would drain all the fuel from the system into a clean container and inspect it closely, the water (if any) will sink to the bottom, whereas any rust or dirt will sort of float around near the top. If you do find rust you can get a new tank or a Kreem gas tank cleaner system, but I would reccomend a new tank, and possibly fuel rail (or you could pull the rail and completely dissassemble it then soak the metal peices in lacquer thinner).

[TS87FC3S]

ok new issues with car,(88 gxl) i fixed all previous issues including idle fluctuations and hesitations by cleaning fuel tank, new filer and plugs, adjusting tps and cleaning throttle body. i also gutted cats and ran a custom 2.5inch cat back, and wired open 6 ports.

Now here are the new issues;
Car has a crazy multiple random misfire at idle, and when u hold it at constant rpm with no load. flipped wires around kinda helped then started doing it all again. (i did the propane check to find leaks and noticed nothing, have pulled plugs they look fine, air filter looks fine, fuel filter has maybe 1500 miles on it, im just kinda lost)

Also at around 6k it feels like car loses all power, nose drops but rpm still try to climb.. so bad that in 2nd foot to floor it wont get to the buzzer.. here is my concern with this rpm still slowly try to climb but wont pull, during this trip i had a hot brake smell i was hard on brakes but not sure if it was clutch or not (xtd stage 3 clutch came with car i put it in and did the break in it has like 2k on it)

[RETed]

Did the car run better before the clutch job?

If so, did you forget to put back the main ground on the starter bolt?


-Ted

[TS87FC3S]

Car didnt run worth a F*ck before the clutch job (the clutch came with the car thats the reason i put in on in case anyone wants to say anything about possible clutch slippage cuz its an xtd)

AND actually i had to add grounds to the car to get it to run decent so i might hve left that ground cable off ill check that in the morning any other ideas on what it possibly could be...

[TitaniumTT]

xtd's suck
ground everything, CAS, AFM, TPS, both rotor housings, etc etc.
check the voltage at the components by backpining the connectors. My bet is there are a bunch of voltage fluctuations causing a ton of problems.
Make sure the coils are getting damn good power
make sure the fuel pressure is where it should be at all RPM's
XTD's suck

[TS87FC3S]

i know that XTD's suck(the pressure plates dont hold), im goin to drive it tomrrow without being hard on the brakes and see if it slips, if it does im buying a new clutch kit oem replacement and using the xtd 6 puck (if it looks good) and scuff the flywheel and use the new pressure plate, pilot bearing and throwout bearing.. ill check all voltages tomorrow and resistance too.. just trying to get ideas on what to check tomorrow

BTW thanks for the help

[TitaniumTT]

puck clutches have little business on a street car. Especially an N/A. There's just no need for that kind of holding power. They chew up flywheels, they can be a bitch to drive, I just don't see the point.

[TS87FC3S]

puck clutches have little business on a street car. Especially an N/A. There's just no need for that kind of holding power. They chew up flywheels, they can be a bitch to drive, I just don't see the point.

Im using the car for AutoX, Drift, as well as dd. im used to race cars and the positive engagement of the clutch and highly prefer that feel, and i want the holding power so that as i upgrade stuff and get more power the clutch will hold.

[TS87FC3S]

So I checked the ground at the starter and yes it was off so I hooked it up but prior to this I had already added extra ground straps, It seems that hot idle has gotten better but when I pull up to a stoplight it still dies or tries to die. And I lose all power at 6k and after driving hard today the clutch seems fine it feels more like in losing spark because as soon as I let off throttle it backfires like alot of fuel in exhaust.. I checked all sensors and all check out except the tps resistance is high but it is corroded so I'm gonna clean it and recheck it...

[TS87FC3S]

Ok so I just went for a drive in the car right after warmup 6k problem is non exsitant after a short drive problem finally occured, also with the firing at redlight whenever I hit the brakes my idle drops terribly so maybe bad booster? Causing rough idle and dieing?

[TS87FC3S]

Other update with brake booster unhooked and both sides blocked off car stills trys to die when u hit the brakes.. Also I can run it on either rotor and it runs smooth no hiccups or anything but hook up both rotors and it has a bad miss I'm completly lost

[RETed]

Compression check?


-Ted

[TitaniumTT]

Im using the car for AutoX, Drift, as well as dd. im used to race cars and the positive engagement of the clutch and highly prefer that feel, and i want the holding power so that as i upgrade stuff and get more power the clutch will hold.

The only upgrade that would warrant a 6 puck on an N/A would be low comp rotors and a big ass turbo. If you want a 6-puck for the feel, fine, but an N/A doesn't make the kind of torque that warrants it.

check the voltage at the coils

[TS87FC3S]

Compression check?


-Ted

I did a poor mans compression check turning it over with the plugs out and it sounded great, im doing a real compression check tomorrow, along with another vaccum check, and ignition system check..

[TS87FC3S]

The only upgrade that would warrant a 6 puck on an N/A would be low comp rotors and a big ass turbo. If you want a 6-puck for the feel, fine, but an N/A doesn't make the kind of torque that warrants it.

check the voltage at the coils

The clutch came with the car as I said and I love the feel I know that it is way overkill.

What should the voltage to the coil be?

[TitaniumTT]

Withen a few percent of what it's at coming off the alternator. If the current is too low the coil can't fully charge and as the RPM's increase etc etc etc

[My5ABaby]

You can also check the resistance of the coils. I believe all 3 should be 1.0 ohms or less (FSM has it so check in it).

[TS87FC3S]

ok so i tested coils all showed fine :banghead: , so i hooked it up to ignition scope i found that my trailing wires are bad so i unhooked trailing and ran just leading to see if same issue, of course same miss, ignition scope looked good... so i hooked up timing light, timing seemed fine... but while i had it hookep up i noticed that one one of my leading wires the signal would drop out with the miss so i put timing light lead next to coil, and found that one side was randomly losing fire, how this is happening i have no fin clue at all.. im hoping this was the issue but not sure if this would cause my dieing at stoplight issue. my buddy has an s5 thats gonna let me use his coil and wires so if that fixes it i know what im gonna need if not ill update... any idea on the dieing at stoplight??? :banghead:

[RETed]

but while i had it hookep up i noticed that one one of my leading wires the signal would drop out with the miss so i put timing light lead next to coil, and found that one side was randomly losing fire, how this is happening i have no fin clue at all.. im hoping this was the issue but not sure if this would cause my dieing at stoplight issue. my buddy has an s5 thats gonna let me use his coil and wires so if that fixes it i know what im gonna need if not ill update... any idea on the dieing at stoplight??? :banghead:

That's normal.
The stock ignition system cannot handle constantly firing everything properly.
(This is why we run CDI boxes to "fix" this problem.)
It's not the cause of your problems, unless it's triggering a larger problem down the line...


-Ted

[TS87FC3S]

That's normal.
The stock ignition system cannot handle constantly firing everything properly.
(This is why we run CDI boxes to "fix" this problem.)
It's not the cause of your problems, unless it's triggering a larger problem down the line...


-Ted

only one side of the coil is dropping out and this is happening at idle.

[RETed]

only one side of the coil is dropping out and this is happening at idle.

That is correct.


-Ted

[TS87FC3S]

"When the pulse switches from high to low, the igniter turns off the current in the primary leading coil winding. Since there is only one leading coil and there is no spark distribution, both leading spark plugs are arced. Obviously, one spark is wasted but with no ill effects."

This being a wasted spark i still do not see how one side of the coil "drops off" and then just starts working again, both sides of coil recieve the same signal and spark.. so im just not seeing how this is normal?

[RETed]

To understand what's going on, you need to understand the dynamics of wastespark ignition...
Most people understand the part about a dual tower coil firing into two "chambers" at the same time, but it's what's happening on the spark plug end that makes it interesting.
A spark plug firing into a compressed chamber requires more power to overcome the (spark plugs) gap - as compared to firing at "0 atmosphere" or outside of the engine.
Add fuel into the whole mixture (no pun intended), and it gets even harder to fire.
A spark plug firing into a chamber that has already ignited is surrounded by ionized gases and particulates (combustion by-products) that helps the arc jump the gap.
Add to the fact that the later scenario is usually at the tail end of the combustion cycle (and starting into the exhaust cycle) which means that pressure in the (compressed) chamber is starting to drop at this point.
Less pressure = easier for the spark plug to fire

Now, let's look at the wastespark, dual tower coil...
It's just a step-up transformer with the two tower (outputs) coupled.
Fire voltage through the low side, and it gets stepped up by the coil depending on the ratio of the windings.
Now, the coil can fire either:
1) tower 1
2) tower 2
3) both towers
Most of the time, it does fire through both.
When it doesn't have enough power, it tends to fire only one side.
Now, remember earlier about the imbalance of the chambers?
Guess which side it's going to fire if it had to pick?
Due to this phenomenon, this is why the coil drops one side occassionally.

rising chamber pressure + fuel = increase resistance to spark plug arcing the gap
dropping chamber pressure + burnt gases = decrease resistance to spark plug arcing the gap

This is why a totally stock ignition FC will sound like this when idling...

brrrrrrrrrrrrrrrrrrrrrrrr, brr, brrrrrrrrrrrrrrrrrrrrrrr, brr, brrrrrrrrrrrrrrrrrrrrrr

Even with the car in top shape and running perfectly, the wastespark is still dropping a spark every so often.
That small hiccup is an ignition misfire.

Partially to blame is the inadequate electrical charging system in the FC.
The stock FC alternator SUCKS.
At idle, the alternator is barely producing enough voltage to charge the battery.
Once the RPM's climb, this isn't much of an issue, so you don't get misfires above idle speeds.

We fix it by installing CDI boxes which totally cures this "problem".
I run a Crane Cams HI-6 myself.
I usually install CDI boxes in all my customer's cars.


-Ted

[TitaniumTT]

I'm really curious to see what the dyno tells us when I test all the different ignition systems. To me, a CDI is just a band-aid for a near stock car but what I believe to be the better answer isn't possible with the stock ECU. While I completely agree with what you're saying Ted, I think a 4 coil system would be a better way to go than putting a CDI box on. The slow rotor speed, I would think, would want to see the slow burn of an inductive coil.
Personally I was running 4 D580 (LS1) coils and never had a hiccup at idle...... except when I wet fouled the plugs once after rebuilding an engine. Those coils I believe are inferior in the higher RPM/higher boost just becuase of a lack of ignition energy. Voltage not being an issue as my alt pumps out 14V @ idle.
Now get to combustion pressures higher than what I'm making and a CDI might give more of a benefit.

[TS87FC3S]

Ok now that helps alot thanks, would runnin a different wasted spark coil help?and mine actually charges at 14.4 at idle not that it really matters... If it not the coil then y would I lose power over 6k and last nite it happened at lik 5k. It happens worse the longer it's been running.

[TS87FC3S]

Replaced Coil with a subaru impreza wasted spark coil (higher firing voltages) and car runs beautifully now, smooth idle and high end rpm is back. I still have shitty wires but doesnt seem to be affecting it at all... i do have a booster issue though, i pump brakes it tris to stall car but brakes feel good and cant here it leak.