Dodge Stealth HELP!! Please: Grassroots Motorsports forum: Grassroots Motorsports Magazine

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March 9, 2011 10:46 a.m. Eardleyf1 New Reader

What started as a head gasket change on my brothers 93 Dodge Stealth has turned into a complete nightmare.

The problem is, we can get the car started but it is misfiring/backfiring and generally running terribly until it dies when you take your foot off the gas.

We made some mistakes along the way, mainly not aligning everything before we took off the timing belt. Now that its back together, we've aligned the cam gears and crank gear with the marked locations several times. After hand turning the engine through a few rotations everything still seems to be lined up. We are both convinced that something is off with the timing but we can't seem to get it right.

Here's what we've done in troubleshooting this so far:

Replaced the plugs and wires Checked the compression (good on all 6) Replaced the ignition coil Replaced the Distributor cap Check to make sure every sensor and connector is connected

I'm lost and need help. This has been a learning experience but now its personal. I just want to figure out what is wrong with this thing.

Thanks for reading through this and for your help.

Adam Amatuer engine ruiner
March 9, 2011 10:48 a.m. Tom Heath Web Manager

Eardleyf1 wrote:

Adam Amatuer engine ruiner

Awesome sig.

One of the local enthusiasts (and now GRM official intern) is big on Mitsubishi 3000 GTs, I'll ask him to check this out and see if he has any advice.
March 9, 2011 10:53 a.m. Eardleyf1 New Reader

Thank you Tom.

My wife and I met you a couple of weeks ago at the office. We were talking to you about the Relay for Life event in town and about what suspension to get for my miata.

I appreciate the help.
March 9, 2011 12:01 p.m. Vigo Dork

The only way a fuel injected car can backfire is if one of the valves is open while a cylinder fires.

The only way that can happen is for cam timing or spark timing to be off. Im pretty sure spark timing is not adjustable on that motor, except that its based on reading the cams which CAN be off.

So it sounds like your timing is still off. I know thats not what you want to hear. Timing belts on those motors are an infamous job for a reason.
March 9, 2011 1:38 p.m. Eardleyf1 New Reader

Thanks Vigo. I actually don't really mind hearing that. At least I'm on the right track in thinking its the timing.

Any suggestions on where to go from here though. I have everything aligned. Is there another way to ensure that the cams are correctly timed?
March 9, 2011 2:24 p.m. Nitroracer SuperDork

I had a similar problem years ago when I was playing with a ford 5.0 and I couldn't figure out why the car was running so poorly. Turns out I forgot to tighten up most of the rocker arms. I'd second the notion that the timing is still off.
March 9, 2011 4:13 p.m. Matt_Smith New Reader

Hello Eardleyf1. Tom sent me to this thread and I'd love to help you. Luckily, the SOHC motors aren't interference motors so you've likely not harmed anything by not aligning the marks when taking the belt off. I'm assuming you have a SOHC motor as you replaced the distributor, am I right?

If its a SOHC, my knowledge is limited as I have only built the DOHC 6G72, but I've read a bunch about the SOHCs. Anyways, onto the troubleshooting...

1) Check the spring tensioner again to make sure your timing belt has kept everything in time 2) Did you take the cams out of the heads at any time during this process? 3) Chances are, you didn't screw up the valve timing. Its so easy to change a timing belt on a SOHC that I'm quite confident you got that right. Did you change the plugs while the heads were off? 4) When you replaced the distributor, did you set the ignition timing correctly?

Do you live anywhere near Daytona Beach? If so, I'd help you in person this weekend.

Oh, and do you have a manual? If not, download one immediately from here: http://www.3sx.com/faq/manuals/

Its free!
March 9, 2011 4:20 p.m. Matt_Smith New Reader

Vigo wrote:

The only way a fuel injected car can backfire is if one of the valves is open while a cylinder fires.

The only way that can happen is for cam timing or spark timing to be off. Im pretty sure spark timing is not adjustable on that motor, except that its based on reading the cams which CAN be off. .

Spark timing is adjusted via the distributor on the SOHC. The DOHC used a Cam Angle Sensor which was also adjustable until 94 when the 2nd Gen DOHC engines picked up the ignition signal from the crank, which then became unadjustable.
March 9, 2011 4:27 p.m. 16vCorey SuperDork

I've never seen this happen on this specific engine, but another thing to check is the key way on the cam gears. I have seen them snap off and the gear spin on the cam. When that happens, all the marks line up, but the timing is very off.
March 9, 2011 4:41 p.m. Matt_Smith New Reader

I just thought of something. Put an inductive timing light on a plug wire and while its stumbling see if you have a constant spark.

Also, while removing and reinstalling the plenum...make sure you didn't damage the MAP sensor.

One last thing, not likely to be the culprit, but so worth the 10 minutes it takes to check it....pull the ECU (very easy to do) and open it up. Looks for burn marks around the capacitors in the center of the ECU. Eariler ECUs have leaky capacitors and can make you chase problems all around the car.
March 9, 2011 6:09 p.m. Eardleyf1 New Reader

Thanks everyone. Matt. It is a SOHC. I didn't have a manual but I just downloaded them from that link. Thank you.

We didn't have the cams out and the plugs were changed after the heads were put back on. I have tried adjusting the timing with the distrubutor but it seems to be too far off to get it right. When I get home I'll try the Timing light, MAP and the ECU.

I'm in Ormond but I'm out of town until Friday night. I'll PM you to see if you might be able to get together on Saturday. It'd be great to have the help.
March 9, 2011 6:13 p.m. Matt_Smith New Reader

Eardleyf1 wrote:

Thanks everyone. Matt. It is a SOHC. I didn't have a manual but I just downloaded them from that link. Thank you.

We didn't have the cams out and the plugs were changed after the heads were put back on. I have tried adjusting the timing with the distrubutor but it seems to be too far off to get it right. When I get home I'll try the Timing light, MAP and the ECU.

I'm in Ormond but I'm out of town until Friday night. I'll PM you to see if you might be able to get together on Saturday. It'd be great to have the help.

Cool. I live off Golf and Nova...by the "Rockin Ranch" I'd love to help out. Just let me know if you would like my help.
March 11, 2011 6:57 p.m. dinogt

In reply to Eardleyf1:

Amateur! Ha, don't sell yourself short. Thanks for the post.
March 12, 2011 1:28 a.m. Opus Dork

Dealing with my fathers 3000gt has been an experience.

First, over the last week, I have learned (from the tech at mitsu) that pre 2000, the ECU's were prone to expire for no reason or indication. No engine light, nothing.

Second, the cars are picky for the parts that are used (at least the vr4 version is) Must use factory plug wires and only double platinum NGK spark plugs. if you do not, there will be issues.

Our computer is being pulled tomorrow to be sent out to be rebuilt.

Your steps seemed logical, but mitsu/dodge were not logical in thinking that the computer would last past 10 years. (most expire in 5 based on my research on the Mitsu boards.)

Good Luck
March 12, 2011 11:17 a.m. dean1484 SuperDork

Kind of dumb but have you checked to see that the plug wires are to the correct cylinder?

If compression is with in spec then odds are you have the valve timing correct. IE the belt is on correctly. BUT just for the fun of it remove the #1 plug and bring it to TDC Then using a wooden dowel rock the motor back and forth with a wrench and make sure that it it at TDC with the dowel. I don't know jack about these motors but if the crank marks check out at TDC via the dowel method then inspect the cams for proper alignment with respect to the crank.

I just played this game with my 924s
March 12, 2011 3:38 p.m. Matt_Smith New Reader

Opus wrote:

Dealing with my fathers 3000gt has been an experience.

First, over the last week, I have learned (from the tech at mitsu) that pre 2000, the ECU's were prone to expire for no reason or indication. No engine light, nothing.

Second, the cars are picky for the parts that are used (at least the vr4 version is) Must use factory plug wires and only double platinum NGK spark plugs. if you do not, there will be issues.

Our computer is being pulled tomorrow to be sent out to be rebuilt.

Your steps seemed logical, but mitsu/dodge were not logical in thinking that the computer would last past 10 years. (most expire in 5 based on my research on the Mitsu boards.)

Good Luck

It was just the first gen ECUs, 91-94 that had leaky capacitors. Its a known issue.

From my experience, I've used many different plugs and wires without fault. If the coil-pack in that car is 20 years old, then that may cause some issues, but I've used copper, iridium, and platinum plugs from various manufacturers without issues as well. "Double Platinum" does nothing for performance, just longevity. Generally I'll run the $1.50 coppers for tuning purposes and when the tune is right I'll switch to the good iridium ones. Depending on the turbos, they may be 1 or 2 steps colder than OEM (otherwise, spark blowout may occur)
March 12, 2011 6:11 p.m. friedgreencorrado SuperDork

dean14's suggestion x2. I can't believe how many times I've gone searching for a problem without checking the wires first. I also once installed a distributor with the rotor 180deg out of time. Drove me nuts, because I kept just moving the the body from full advance to full retard with no results.
March 12, 2011 11:02 p.m. Vigo Dork

Spark timing is adjusted via the distributor on the SOHC. The DOHC used a Cam Angle Sensor which was also adjustable until 94 when the 2nd Gen DOHC engines picked up the ignition signal from the crank, which then became unadjustable.

Oooooooooops. Missed a major context clue there about the distributor.

So my advice was pretty far off. The sohc 3.0 is actually an easy motor to do timing on. Ive got 1 in a running car and 3 sitting on the ground. Im about to swap one into my caravan.

Anywho, my comment about the backfires is still true. So, the ultimate thing to do is take off the rear valve cover, distributor cap, and spark plug from number 1 cylinder (which is closest to distributor iirc). In a stealth the distributor is at the right rear of the engine bay, right? Put the #1 cyl to tdc. This should correspond to the mark on the crank gear lining up with whatever it lines up with, but verifying with a screwdriver down the spark plug hole is easy. So when #1 is at TDC both valves should be closed which means they will be all the way up. Then look at the ignition rotor. It should be pointing very near to the #1 terminal on the distributor cap. If its not, turn the distributor until it is, or take it out and respline it if its way off (i forget if that one is keyed somehow).

If youve got #1 at tdc and the valves are closed and the ignition rotor is pointing to the #1 terminal, it's not a cam or distributor timing problem.