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DSMnewguy999

Probationary Member
12
4
Nov 27, 2023
Minot, North_Dakota
I'm new to the DSM world, kinda fell into having a 1990 Eagle Talon TSI/Manual. (Red car) It sat for about 20 years, (registration tags on it when a friend bought it said they expired in 2003) I bought it from him after he owned it for a month and said he didn't want it anymore.

Another good friend of mine has been trying to help me with getting me some decent "ERA" specific aftermarket parts from a guy he knows that wound up selling me another 1990 Eagle Talon TSI/Manual (Purple car) parts car with a good title.

Been enjoying the car for the most part but I have been running into a few issues with it due to the engine not catching its itself when letting the clutch out with any kind of higher RPM and stalling. (RPM higher than 1k rpm and letting off will let it die unless I left foot brake and catch the RPM back to an idle of about 750)

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Welcome to the DSM world. That’s a confusing description of the symptoms, and I can’t tell if you’re discussing a clutch issue or an engine/fuel issue. (And is this all related to the red car, which sounds like mostly stock?)
Can you simply let the clutch out at slightly above idle without a stall? How do you keep it from stalling? Does it change if the motor is cold or warm? If it’s not a clutch problem, I think you’re describing the symptoms of a boost leak. That’s relatively easy to test/ diagnose with a boost leak test. Does it run strong once you’re underway, say from 3 to 5k rpm?
 
My apologies, the stated symptoms all related to the Red car. It's is all factory, OEM if you will.
If I were driving down the road at let's say, 25mph, in Second Gear at idk about 2k/3k Rpm and I pushed the clutch in, the Rpm will fall and the engine will not catch itself and will stall out. It does not change with engine temp. The engine pulls very well through 3k Rpm up to 6k Rpm. (letting off throttle not wanting to push it terribly hard)

Fuel pump, fuel tank, fuel pressure reg. , fuel filter, spark plugs/wires, air filter have been replaced and an oil change has been done.

A friend of mine had tried helping me and had unplugged the ISC/IAC with the car running and we had determined that it's not working, so, I did purchase an ISC/IAC but didn't check which one the parts store ordered before finding out I received a +91 version. (didn't know I needed one that has an external wiring pigtail) Looking for the correct part now with little luck.

So far the potential "fixes" have simply been assumptions with little true testing of the thought.

For when coming to a stop. The way I have been able to drive it is by braking with my Left foot, while keeping Rpm up with my Right foot still on the throttle keeping the Rpm up and slowly allowing the Rpm to come down as I stop. Once the Rpm is around 1k/800 Rpm I can let off the throttle completely and it will idle around 700/800 Rpm.

Other wise when just driving it with Flowing traffic it's been able to been driven in a normal capacity, up shifting and down shifting as needed of course.
 
This kind of engine stall is caused by many factors. Such as improper throttle body adjustment, boost/vacuum leak, improper valve and ignition timing, bad sensor, bad ECU, bad wiring, lightweight flywheel, crankwalk etc etc. So usually it's hard to pinpoint the cause in one shot. Since there are many possibilities, you should start from something basic, like checking for the throttle body adjustment, all sensors and wiring, leaks, valve/ignition timing, and adjust or fix if necessary. And then see if the engine stall issue would be gone or still remain.
 
This kind of engine stall is caused by many factors. Such as improper throttle body adjustment, boost/vacuum leak, improper valve and ignition timing, bad sensor, bad ECU, bad wiring, lightweight flywheel, crankwalk etc etc. So usually it's hard to pinpoint the cause in one shot. Since there are many possibilities, you should start from something basic, like checking for the throttle body adjustment, all sensors and wiring, leaks, valve/ignition timing, and adjust or fix if necessary. And then see if the engine stall issue would be gone or still remain.
It definitely shouldn't have a LW Flywheel.

Because I don't understand how it would affect it, how would crank walk cause this kind if issue during Rpm deceleration but not cause a large issue while gaining Rpm?

It does need to have a timing belt kit done just due to the age and will be getting it done soon enough so that should be able to get the timing checked off the list.

The car did come with a decent original service manual.

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That helped a lot to better understand the car’s condition. You will find that while the 1990-1994 dsm are rather rare and with limited replacement parts available, the 1990 specifically has several items that were changed after that first year, making them even more obscure. Throttle body is one such item. It fits the basic symptoms of IAC malfunction, which should keep enough throttle open to prevent stalling. If you can get the right part, I’d say the odds are in your favor.
 
That's what I'm certainly hoping, I will also have to conced that I have been a terrible auto enthusiast trying to fix my own problems. I haven't really tried to fiddle with the service manual yet. Trying to use the internet and videos to try and diagnose or even find a quick fix right away.

The plethora of parts I've gotten are certainly going to change how the engine runs. When it's not 20°F out so I can actually put them on the car.

Parts that I've received...
2.5in stainless turbo back exhaust
DSM Link already installed on a separate ECU
Busher racing front mount intercooler with the piping kit and an already cut bumper to fit that intercooler
There's other parts but I haven't gone through them very thoroughly, the big parts are a bit easier to know what they are of course.
 
It definitely shouldn't have a LW Flywheel.

Because I don't understand how it would affect it
A LW flywheel would make the engine speed response faster. Faster engine speed dropping would be a cause of engine stall.
how would crank walk cause this kind if issue during Rpm deceleration but not cause a large issue while gaining Rpm?
If you press in the clutch pedal in a crankwalked engine, you are technically braking the crank rotation by making more friction on crank. It causes the engine speed dropped and sometimes become a cause of engine stall. At higher RPM you have more torque and oil pressure, so just don't notice easily, since at low rpm the symptom is more obvious.
The car did come with a decent original service manual.
That's a bible. Since the car is 30+ years old, proper maintenance by following the FSM would be the best medicine in many cases.
 
I can see how pushing the clutch in would affect a crank walked engine now, makes a lot of sense.
I've known that a light weight would be nice for relieving weight from the rotating assembly and to help gain rpm faster, but never thought much about how it would affect rpm coming back down to idle, very neat.
What would be the best way to check for substantial crank walk? (Without taking the engine out)
Definitely going to be doing my best to keep the manual in as nice a shape as I can while still using it to the best of my ability. Just wish the exterior of the book was in better condition, the pages honestly don't look like they've even been turned.
 
What would be the best way to check for substantial crank walk? (Without taking the engine out)
You would find many posts here or videos in google how to check it. Technically you measure side to side crank play by a dial Indicator. In case if you can move the crank by pulling/pushing the crank pulley by hand, then it has already been terribly walked.
But this really is the worst case scenario. If you can't move the crank pulley by hand for now, like I said above that you should start to check from something basic and common.
 
You would find many posts here or videos in google how to check it. Technically you measure side to side crank play by a dial Indicator. In case if you can move the crank by pulling/pushing the crank pulley by hand, then it has already been terribly walked.
But this really is the worst case scenario. If you can't move the crank pulley by hand for now, like I said above that you should start to check from something basic and common.
Got a good point, and that makes sense.

I would install the new ECU with ECMlink. It would help a lot with diagnosing your drivability issues.
I guess I'm gonna try and install that here sooner than later.

Thank you guys for the shared info and suggestions as to what I need to do and check to get the cars issues ironed out. I'll post an update as soon as I have something to report. 👌
 
Regarding the crank walk; I thought that afflicted mostly the 7-bolt motors, and this is a 1990, presumably still with the original 6-bolt motor.
Overall, my advice is to follow the very wise advice in the tech pages for new dsm owners and the recommended path for performance upgrades. Get the car running right and do normal maintenance (timing belt, as you said, but also fluids, filters, hoses, adjustments) before you move ahead with modifications.
Then you will have good baseline to know if the mods are having the correct effect.
 
Regarding the crank walk; I thought that afflicted mostly the 7-bolt motors, and this is a 1990, presumably still with the original 6-bolt motor.
Yes more often on non revised 7 bolt than 6 bolt, but it happens to 6 bolt, too. It doesn't matter 6 or 7 bolt, if once thrust bearing get worn/damaged for some reason, it becomes a crankwalk time bomb.
 
Welcome to the club! Always nice to see another DSM back from the ashes.
Regarding your stalling issue:
My first thought is the idle switch. It acts as a throttle stop but also tells the ECU when you're at zero throttle. It's a switch on the back side/top of the throttle body and has a single wire attached to it. A lot of times this wire breaks off or just falls off the electrical lug and the ECU no longer knows when it should idle. It also requires a TB ground strap, which is usually a small plate on top of the TB attached to one of the 12mm mounting bolts with a phillips head screw on top of the TB. Snap a few pictures of the engine bay and post them here. We can pretty easily identify if it's an idle switch issue.

Another poster suggested swapping to your ECMLink ECU, which could solve the issue all by it's self. Capacitors in your original ECU may have leaked and caused corrosion, and usually the first thing to go is the idle circuit.

Sounds like you're already on top of the ISC. It could be this too, but don't be surprised if it's not (see ECU capacitor corrosion). Along with the ISC, make sure your BISS is not missing and has a good o-ring. Use that FSM and look up how to set the curb idle properly (hint, it's not just adjusting the BISS).

No matter what, perform a boost leak test, because a leak anywhere in the intake can and will cause idle issues. Not to mention issues while under boost.
 
Welcome to the club! Always nice to see another DSM back from the ashes.
Regarding your stalling issue:
My first thought is the idle switch. It acts as a throttle stop but also tells the ECU when you're at zero throttle. It's a switch on the back side/top of the throttle body and has a single wire attached to it. A lot of times this wire breaks off or just falls off the electrical lug and the ECU no longer knows when it should idle. It also requires a TB ground strap, which is usually a small plate on top of the TB attached to one of the 12mm mounting bolts with a phillips head screw on top of the TB. Snap a few pictures of the engine bay and post them here. We can pretty easily identify if it's an idle switch issue.

Another poster suggested swapping to your ECMLink ECU, which could solve the issue all by it's self. Capacitors in your original ECU may have leaked and caused corrosion, and usually the first thing to go is the idle circuit.

Sounds like you're already on top of the ISC. It could be this too, but don't be surprised if it's not (see ECU capacitor corrosion). Along with the ISC, make sure your BISS is not missing and has a good o-ring. Use that FSM and look up how to set the curb idle properly (hint, it's not just adjusting the BISS).

No matter what, perform a boost leak test, because a leak anywhere in the intake can and will cause idle issues. Not to mention issues while under boost.

I will make sure to grab some photos tomorrow if there is still enough light out. (No garage life)
Ordered a new in box ISC/IAC on Ebay earlier today. I know that the Idle Switch is definitely still there and hooked up but I will have to check for that Ground strap.

The Capacitors in the ECU makes a lot of sense, I had an '84 C4 Corvette and the speakers all had their own Amps with Capacitors that were all rather... puffy and dead. Need to get a friend of mine over so he can go through all the parts with me and he can hook his laptop up to the new ECU. Supposedly that ECU has tunes on it for about 450hp from the 1G it was in.

Will have to figure out how I'm gonna do a boost leak test, but I'm sure one of the guys in my area's car group has the stuff to get that done.

Only thing I don't have for the BISS is the cap sadly. I've only messed with it once using a procedure I actually found on the forum prior to joining, to get the Rpm lowered back to that 750/800.
 
The car has been sitting for many years, you should remove the throttle body and clean perfectly by carb cleaner including the tiny air passage and set everything by following the FSM.
The idle position switch is a simple on/off switch, you can inspect easily. Most of cases its wiring is more problematic.
The 90 ISC is different from the 91+. The 90 ISC comes with a pigtail. Just in case if you are not sure about the difference between 90 and 91+.
Supposedly that ECU has tunes on it for about 450hp from the 1G it was in.
You would need a new dedicated tuning for your own setup. Forget about the tuning came from the previous owner.
Only thing I don't have for the BISS is the cap sadly. I've only messed with it once using a procedure I actually found on the forum prior to joining, to get the Rpm lowered back to that 750/800.
The RPM is based on a certain throttle plate position and base ignition timing. So setting the RPM by adjusting the BISS without setting the throttle plate position and base ignition timing would be a double work.
 
The car has been sitting for many years, you should remove the throttle body and clean perfectly by carb cleaner including the tiny air passage and set everything by following the FSM.
The idle position switch is a simple on/off switch, you can inspect easily. Most of cases its wiring is more problematic.
The 90 ISC is different from the 91+. The 90 ISC comes with a pigtail. Just in case if you are not sure about the difference between 90 and 91+.

You would need a new dedicated tuning for your own setup. Forget about the tuning came from the previous owner.

The RPM is based on a certain throttle plate position and base ignition timing. So setting the RPM by adjusting the BISS without setting the throttle plate position and base ignition timing would be a double work.

I'll get the throttle body cleaned this weekend.
I'm aware that I'll need the ECU tuned or reflashed for what my engine. I was just sharing what it was on and how much HP the guy that owned it previously got with the mods he had on his car before I got the ECU. Definitely can't wait to get this thing dialed in and be able to reliably daily/autocross it.

Only reason I messed with the BISS was to get RPM back to where it should be. (BISS was jabbed all the way in when I got the car) The car definitely needs a lot of once overs and standard replacement parts I'm general I'm sure.
 
Only reason I messed with the BISS was to get RPM back to where it should be
For avoiding the engine stall (in case if you would need it in future), screwing the idle position switch in to push open the throttle plate a little bit more to make the RPM a bit higher would probably be more effective than messing with the BISS. When I was using a LW flywheel, I was doing this way.
 
For avoiding the engine stall (in case if you would need it in future), screwing the idle position switch in to push open the throttle plate a little bit more to make the RPM a bit higher would probably be more effective than messing with the BISS. When I was using a LW flywheel, I was doing this way.

Gotcha, hopefully I find a few things that can be fixed so I don't have rig too much stuff. Preferably no rigging things together.
 
Gotcha, hopefully I find a few things that can be fixed so I don't have rig too much stuff. Preferably no rigging things together.
Forgot to mention one thing, if you would replace the ECU with the one w/ ECMLink, make sure which year that ECU is. If the ECU is 91+, you would need to switch pin #6 and #14. Otherwise you would have a unstable idle and the engine won't run good.
 
In terms of your original ECU, I had great service on my 90 by sending it in to ECM tuning (vendor on this site) for general inspection and cap replacement. Mine checked out great, and they replaced the caps as precaution, but it’s ot something I would be qualified to handle myself, so it gave me a lot of peace of mind. Perhaps using a new, properly flashed ecu will work great, but it does add some new variables into your troubleshooting sequence. ECM only charged me like $75 (3 years ago) and I had it back in around 10 days ( the majority of which was shipped time). Highly recommend it.
 
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