Hi, I have a 1988 Chevy s10 with a 2.5L 4 cyl engine. My newly installed exhaust manifold is glowing red (like the old one did). The car can’t get past 50 (and that’s with the pedal all the way to the floor). It idles somewhat rough and gives off a small backfire every now and again when it’s being driven around 40-50mph.
As stated, I’ve replaced the Exhaust Manifold but I’ve also replaced the Cat, cleaned the Intake Manifold, and checked the timing (wiggles very slightly around 0 which I’m told isn’t bad). I’m about ready to drive this car off a cliff! What is causing these two symptoms and what are your recommendations for fixing it?
It sounds like an exhaust restriction.
Try disconnecting the exhaust pipe right after the cat. Now drive the vehicle. Sure, it’ll be loud. But if the power is restored with the exhaust system disconnected from the cat, look for a restricted muffler.
Tester
…and don’t park near my red Prius…
I was going to say some other exhaust restriction too. Check it with a vacuum gauge. If the vacuum falls off as the rpms go up with no load, then you’ve got a restriction.
…but…I think you’ve got a bad timing chain. The random backfire is a clue as is the bouncing timing mark.
Do the test with the distributor cap off. Rotate the crank with a socket unit the rotor starts turning. Reverse it and figure the degrees you’re tuning the crank without the rotor turning. I think you’re limited to about 12 degrees of slop.
I think your cam timing is way, way off, or you’re using the wrong ignition timing mark.
Is the timing done from the crank pulley? Maybe the pulley is off.