ShadeTreeJack

1998 3.1L Malibu 165k miles. was running fine quit running while driving.
a couple times it stalled and restarted. now won't run right.

it starts but runs extremely poorly - if I hold it at full throttle, it goes to about 1000 rpm for a couple seconds, then quits. with starting fluid, it reaches 2 - 3,000 rpm for 5-6 seconds before dying. while cranking, it sounds uneven, not quite a back-fire, but not a smooth even sound. sometimes has a knocking sound. all this makes me think the timing belt jumped a tooth. BUT -
could this be crank sensor? - the stalling a couple times before the final time makes me consider this - would it act like this?

Also only code is 300 - random misfire

MDTAHOE

Check the fuel pressure

ShadeTreeJack

Fuel pressure is good. I am going to check the ignition module. I read another thread that said Autozone can test them -they know me pretty well there. I am also removing the IAC EGR and cleaning them. Also have compression test on the agenda.

ShadeTreeJack

It stopped starting altogether.

I replaced the 24X crank position sensor, Cam sensor and the timing chain and sprockets. The old timing chain was loose and off by one tooth , so I really thought it was the problem.

Still no start. not even with starting fluid.

I have checked the ohms of the fuel injectors all about 12.7 - OK
Noid light test - OK
I have spark. I should probably install fresh plugs.

compression is weak (60-70 psi) but it seems like it should start.
maybe a leak down test is in order.

I am at a loss for what to do next. any help?

ShadeTreeJack

I rechecked the compression and replaced the spark plugs.

these are the compression numbers in psi
1-150
2- 90
3 - 120
4 - 60
5 - 0
6 - 20

Still have spark and noid light. no start, but also no backfiring

MDTAHOE

Car will not run at the specs. Cylinders maybe washed with fuel. Add 2 ounces of oil too each cylinder, turn it over by hand a few times then either re check compression or try to start it. How do you know the fuel pressure was good. Check the engine vac while cranking. Also you may want to try to unbolt the exhaust. However none of this is relevant if the compression does not come up.

ShadeTreeJack

Several friends have been insisting I must have the crankshaft 180 degrees out that is that the piston may be on the compression stroke not the exhaust stroke. I insist it makes no difference to the crank; TDC is TDC regardless: the camshaft must be aligned correctly when the crank timing mark is with the #1 cylinder at TDC. OK so I set it the way my Chilton's Malibu manual says to set it: timing marks point toward each other: up on the crank, down on the cam. ( it doesn't start) I reopened the cover today o see if it was as I thought I set it and it is. I couldn't find my Malibu service manual, but I found my third gen Camaro manual: IT SAYS: cam gear timing mark is supposed to be UP when the #1 cylinder is TDC for the V6 models, which includes the 3100. So which is it?

ShadeTreeJack

I was thinking of giving up on this engine, so I searched for a used engine. I found one 'for parts' that had a brokem cam; Aha! broken cam - that fits the symptoms. I pulled a rocker cover and cranked the engine. Two rockers rocked and 4 didn't move. bad cam. trying to decide whether to replace the cam or put in the used engine I got for $100.... looking back I am surprised it started and ran rough on what must have been two cylinders

jnlewis48

I have a 98 Malibu 3.1 liter engine. I was told that my timing chain was unable skip/jump because of the make of the motor? is this true?

jnlewis48

another mechanic told me the timing chain did skip. I'm confused...