My wife has an '88 duke as her daily driver. Just yesterday it decided it didn't want to start. It will crank and fire but I'm getting backfiring through the intake. Took the cover off and it looks like a KISS concert. The timing seems off somehow. I pulled the oil cap off and can see that the rocker arms are still moving so the gear didn't strip.
Has anyone ever had a gear skip a tooth? I've had some weird things happen lately so I thought I'd check. If not I gotta suspect something electrical, probably crank position sensor. Sound plausible?

When I had a duke (my first Fiero) the timing gear stripped on me. They are some composite plastic or something.. It is verry possible for it to round off slightly and maybe skip a tooth ot 2. But that means it won't be long for it to fail completley. so if you suspect timming, change it all out. Depending on how attached you are to the motor, you can get 2200's from J-bodys for dirt cheap and they bolt to your trans. Not much of a power upgrade, but better than the duke and cost about as much as an oil change. LOL!

cheers!

I think I'd rather switch motors than do a cam timing gear job right now. But it's her daily driver. I've got a motor waiting to go in, it's just not ready yet. I guess I'm not ready. It's cold outside, even in the garage.
Is there any difinitive test to determine if the gear has slipped a tooth? I just can't believe with the torque on the gear that it would slip and not strip.

My guess would be a compression test... That's about the least evasive test, otherwise you start tearing in to the engine that you really don't want to invest into anyways.

They won't skip.... once it starts, it strips.

The check engine light is on but it may just be because it won't start. Does the computer diagnose a bad ignition system?
Sounds like a compression test would help diagnose a slipped cam gear. It's easy enough to do and I'm feeling really lazy.
All summer and NO problems!!! Why in the winter? When it's cold?
OK, I'm done whining.
ECM?

Why don't you find out what the check engine light is trying to tell you?

quote Originally posted by Gall757: Why don't you find out what the check engine light is trying to tell you?

x2. if the timing gear went, the rocker arms wouldn't move. I have experienced this first hand. Check the service engine codes and get back to us. otherwise you will be wasting your time, as the problem could be simple.

I already know what it's saying. "What's that stuff you have in your wallet? I want some!!!"
Cars and kids, similar in sooooo many ways.

They don't skip a tooth, they strip at least a third of the gear clean off. I've had it happen to me twice over the years and have seen a few more on various Dukes in different cars, they never skip a tooth.

quote Originally posted by Mytime: I already know what it's saying. "What's that stuff you have in your wallet? I want some!!!" Cars and kids, similar in sooooo many ways.

But... you are not listening to what it is saying.... you are ignoring it

5 minutes is all it takes to get the code.

Check codes and compression.

some testing -

Make sure EGR is closing - could be stuck open.

Make sure cat is not clogged - pull O2 to test.

Then on to igntion and fuel delivery.

BTW. This is pretty much how my '88 was running when one of the coil packs went out (it was cracked and water got to it).
So, that is why you need to check the codes, then check the basic things (EGR, fuel spray). I doubt it is timing or compression... it probably is ignition.... at least from what we know from your description.

[This message has been edited by jaskispyder (edited 02-08-2013).]

Great info. I was leaning towards ignition components now that I've seen the rocker arms moving.

quote Originally posted by Mytime: Soooo, it seems the coil used for the 3.8 SC is the same coil as the 2.5 DIS. That's a swap out that will save me a trip to the store. Didn't know that.

CHECK YOUR CODES BEFORE YOU DO ANYTHING!

Yes MOM!!
Just stuck at work and looking up everything I can before I dig into it.

quote Originally posted by Purple86GT: When I had a duke (my first Fiero) the timing gear stripped on me. They are some composite plastic or something.. It is verry possible for it to round off slightly and maybe skip a tooth ot 2. But that means it won't be long for it to fail completley. so if you suspect timming, change it all out. Depending on how attached you are to the motor, you can get 2200's from J-bodys for dirt cheap and they bolt to your trans. Not much of a power upgrade, but better than the duke and cost about as much as an oil change. LOL! cheers!

Can you give me a bit more info on the 2200 J-body swap? As in what model, years and can it be done using the OD trans?

Pete

quote Originally posted by Mytime: Yes MOM!! Just stuck at work and looking up everything I can before I dig into it.

Just trying to save you some time/money

BTW, had a problem with an '88 duke that had a sticking injector. Boy, was that fun.... testing it turned up nothing, but finally I got it to stick "on" and that was my indication it was bad. swapped it out and all was well. Strangest problem, came out of nowhere, right before I wanted to sell it

Oh I appreciate the help and advice.
Right now on initial evaluation I know the injector is working. Shoots a pretty fireball when I have the air cleaner cover off. Glad I wasn't looking down the throttle body when it did that.

quote Originally posted by Mytime: Oh I appreciate the help and advice. Right now on initial evaluation I know the injector is working. Shoots a pretty fireball when I have the air cleaner cover off. Glad I wasn't looking down the throttle body when it did that.

Yeah, mine was real fun when it stuck ON... dumping fuel into the intake!

BTW, I had the coil pack die when it was snowing (heavy lake effect) and the car had to be towed home (I wasn't driving). I pulled the coil packs and there was the crack (full of water also)

Well, the culprit was a bad crankshaft position sensor. It had a crack going completely around it about midway down the shaft. Heck of a lot easier to replace than a cam gear. Car runs good now but is throwing a code 45, running rich. Gotta track that down now.

Unplug the battery for a minute then see if the code comes up again after driving it.

[This message has been edited by jaskispyder (edited 02-10-2013).]

Yup, did that. From what I've read here it may be the MAT sensor. Injector doesn't appear to be leaking.

Could be o2 sensor also... any other codes?

Yup,12.

Take the ignition module to a parts store had have it tested. They'll do it for free.

12 is good.

[This message has been edited by jaskispyder (edited 02-10-2013).]