TensorWorl

I bought a 94 SC400 and decided to do some maintenance. I replaced the timing belt, tensioners, water pump and pulleys and went to start the car. It started but was missing on several cylinders. I checked the timing and it was correct and I went to check the plugs and wires and the wires literally fell apart the were to old and brittle. So I replaced the plugs, distributor cap/rotor and wires. I also swapped out an ECU from another SC400 I have the runs perfect but has a bad trans. I went to start it and it started but would misfire badly and only got worse for about 15 seconds before it died and wouldn't start again. There was a strong smell of gas like the engine was running really rich. I checked and I'd put the wrong ECU in the car that I knew ran really rich probably from the capacitors being bad. So I put the good ECU in the car and it still wouldn't start. I removed the plugs and they were covered in gas. I cleaned them and put them back in but it still wouldn't start. There is also this slight sound like a back fire when I first try to start the car.

My question is: What is the next step? Do I need to replace the plugs? Is there something else I need to replace that the rich ECU would likely have fried? I have two extra SC400's so I can trial and error parts but I am not sure where to start. Thanks in advance.

TensorWorl

So I waited a few hours and tried to start it to see if the plugs dried out. Sure enough with the different ECU it starts, idles rough and slowly dies over 20 seconds and smells like it's running very rich but no smoke. I also removed the plug wire and tested spark and it has good spark. So I don't think it's the plugs are fouled or anything like that. I think I am getting way too much fuel but not getting any smoke out the tail pipe. I am going to see if there are any CEL's tomorrow but I don't see any while it's running.

zeus87gn

Don't know where your at in your repair now but I fought a similar issue

Come to find out I aligned the cams incorrectly when I installed the timing belt
I was lining up the cams using the tabs on the BACK of the cam gears
The correct cam gear marks to use are on the FRONT of the cam gears

RudysSC

^ I have a feeling timing may be your issue if you did the belt yourself. Check on this gentlemen's suggestion before moving forward. Any CEL on during this event?

TensorWorl

I initially thought it was the timing belt except it ran fine after I replaced the belt but before I did the wires. It also would run fine for 5-10 seconds if I let it sit for an hour or so. I changed the fuel filter and played with it for several hours. Then I remembered I had also moved the car between doing TB and wires and maybe it was low on fuel. Two gallons later and sure enough it runs fine. I feel really stupid. :/ It's still down a cylinder but it runs and drives. I can at least trouble shoot it when it runs. lol