I got a 96 3.8 RS that has gave me trouble after trouble starting! I've replaced the switch, I've bypassed the key with resistors and every time I've "fixed" something it lasts a few days or weeks and then without notice BOOM it quits starting again! the engine cranks over but won't start (NO SPARK). I've done just about every test that I can find to do and still haven't found anything that works. I'm bout tired of it, but I love the car, its the NOT STARTING I HATE!
My question is this how big of a can of worms would be opened if I got a 2.8 CARBED & DISTRIBUTOR IGNITION or a 4.3 CARBED & DISTRIBUTOR IGNITION and replaced the 3.8? I swapped a 350/350 turbo into my 98 Sonoma and its great! granted there were a few "issues" to resolve BUT its done. I know the fuel would have to be regulated down to run the stock pump or do like my Sonoma run a mechanical one. Or could the 2.8 be ran TBI? The reason I ask is a buddy has a good TBI 2.8 with harness and computer. The next "problem" is the manual transmission bolting up to the swap engine, at least shifting wouldn't be an issue! I know the 4.3 wont bolt up to the 3.8 bellhousing but the 2.8 might. I've already found alot of the info on tranny/bellhousing/bearing combos that work together.
If this isn't feasable the car has GOT TO GO! I'm tired of it costing me insurance, tag, cutting grass AROUND it etc.

Any opinions or ideas?

 

I'd say go back to the very basics to get it to run right.

With that said, it is not worth it to go that direction. Especially with the 2.8 as it's a downgrade from the 3.8. The 4.3 would be interesting, but again, it would not be worth the hassle.

If you really care for the car, I'd suggest taking it to a recommended shop and have them see if they can fix it or have any ideas on something you may have overlooked.

 

Ugg,, a 3500 lb car with a 125 HP 2.8. Even with the 185 HP 3.4 the 4th gen is under powered. Compared to the 2.8 the 3.4 is a torque monster. 4.3 is a decent low end torque motor but I do not think it would out run a 3800. My son inlaw has a 2002 S10 5 spd extream. He borrowed my Camaro, he thinks the Camaro is faster. To be fair I think the truck is a little heaver.

Either engine would be a night mare to swap. The 2.8 from a Camaro would bolt in, the 4.3 would cost money just to get the block installed and an oil pan made up. Head over to the project section and check out the conversion. The guys that do it spend a LOT of money getting rid of all the things that will not workout with the PCM to run things. Getting the 4.3 mounted in the car would cost more then it will cost you to fix your car. Getting the 4.3 mounted will be the easiest part of the swap.

No spark is not hard to fix by a real mechanic. A cranks sensor sends a signal to the PCM the PCM sends a signal to the ignition module the ignition module fires the coils. A good scan tool will tell the tech if the PCM is receiving the signal from the crank sensor and if it thinks it is out putting a signal. If its recieving and not out putting due to the VATs system he will know within 5 minutes. If the PCM thinks it sending the signal then you just check that the ignition module is getting the signal. If it is then test the module and coils. A GM tech would have a spare "test" module and coils on his shelf.

Like I said for real mechanics no starts are easy. It is the cars that no starts once a month or have problems once it a while that are the challange. It can be very hard to figure out what was wrong 3 days ago on a perfectly working car.

 

YOU DESCRIBED MINE TO A TEE! Thats EXACTLY how it does, crank & run fine today, tomorrow but then whenever and whereever wont start. just the other day I had to charge the battery, put it on, tried it NO START. just a littlewhile later it cranked right up then next day wouldn't crank agai and hasn't since!
yeah figured the swap was not worth it but I aint spending no $500 to &1000 to get it fixed, i'd scrap it first or part it out.

 

Sounds like a classic fuel pump, I have had people try for hours to start their cars and the next morning it fires right up. A week later not start. Are you sure its no spark. All the mechanic needs is to get the car while it will not start. Its easy to trace at that point.

 

Yes I'm certain it doesn't have spark. I hooked my spark checker up to a plug wire, grounded the checker and cranked the car and no spark. The weird thing is there has been times that it wouldn't start and I hook up the spark checker to see if it is and as soon as I hit the switch it fires right up. As for the fuel pump I can hear it come on then off and if you are under the hood you can feel the fuel lines move when the pump activates.

 

The VATS system removes spark and will not turn on the injectors when the engine cranks. Since you started messing with and trying to bypass the VATS system I would start looking there. As far as I know only a Tech II can bypass the VATS for testing purposes. A Tech II can also read the BCM to determine the go/nogo signal from the VATS. Other scan tools may also be able to detect the go/nogo but the average autopart store scanners will only read codes. It seems to me that the issue is going to be alot easier to fix than swapping out the engine. As for the ignition system the DIS used in the 3800 engines is pretty robust and not prone to major issues. The main components are the CKS, Ignition module, Coils, and the PCM.

The CKS delivers the crank position to the PCM, the PCM determines the timing based on engine load from other sensors or in limp home mode from a pre determined map. The PCM then sends a trigger signal to the ICM which fires 1 coil (2 plugs) at a time. One spark is wasted and one is for the ignition of the cylinder. That is it simple as that

Massey

 

I wasn't messing with and trying to bypass the VATS system, I bypassed the resistor in the key with info found on this site because of an issue with the security light coming on. And yes it did work perfectly. The car ran fine after that. The NO SPARK issue has been happening randomly for quite some time now. The fuel pump is working and the injectors are working and the ICM IS getting power, the crank sensor IS getting power and IS pulsing on BOTH sides back to the ICM, power IS getting through the ICM to the coils, The last test I done showed the switching signal IS NOT getting through the ICM to the coils. That test says the ICM is bad. I tried another ICM and had the same results. I've had BOTH ICM's tested at Advance auto parts and they BOTH tested good. Thats about all I've tested.

 

If the ICU is not getting the signal from the PCM then the associated wiring or the PCM are the cause.

Massey