so here's the problem, every now and then i start up and it gets a huge miss-timing. cylinders miss fire and it reeks of fuel. the engine shakes. also when cruising the engine shake is minimal but under even the slightest acceleration, it shakes like no other.
ive replaced alot of the ignition parts b/c thats what it feels like it is since it only does it sometimes on startup.
new parts:

• plugs(gapped to .35)
• wires
• dist cap and rotor
• crankshaft position sensor
• tps, also adjusted
• iac
• ignition control module
• coil pack
• ign switch

ive also checked the grounds aswell.
any kind of input would be appreciated. im mind blown and so is the mechanic

 

Just taking a guess , maybe bad fuel pump.
Have you tested the fuel pressure at the fuel rail ?

 

as of a week ago it was only 1psi lower than standard.

the best way i can describe it is a "missfire when warm".

 

Man you.replaced the.iac... I hope you solve this cause I've been chasing a misfire myself. I was thinking the exhaust is clogged up. I thought about the iac today. I have done the full tune up and tps and map. The other thing I think it may be is the cam position sensor because it effects injector timing and firing.

 

the camshaft position sensor and map is something i havent replaced just yet.

does your misfire come and go based on ignition?

mine will start/run fine when its cold but as soon as it warms up and if i turn it off and back on, itll start misfiring.

 

I get a misfire when its idling and it cleans up as it revs. I get a fuel smell too though. I'm going to test the cam position sensor soon.

 

The stator in the distributor generally won't cause any driveability issues that you'd notice. The MAP will. Check the integrity of the hoses/piping from the throttle body to the MAP. Any cracks, splits, melted areas, loose fitting hoses can cause an extremely rich condition.

 

Stator won't cause misfire or fuel smell?

 

Not on a Renix. All it does is signal the ECU to fire the injectors sequentially, matching the firing order of the engine. If it fails, the ECU defaults to batch firing the injectors. The only way you'll ever know if yours is bad is by testing it.

Only way I've ever detected it is by hooking up to the factory tester and observing it in real time.

 

The map is something I should look into replacing?
All my wires have just about .41 of resistance so that shouldn't be a big problem right?

 

Sounds like a lotta resistance. Leroy you probably should add a separate ground. Cruiser you have any ideas on this stumble and random miss? I've already done map and lines. No vacuum leaks. I was thinkin iac on mine but this guy replaced his already. I know it takes special equipment to test it too. Expensive little part. The rest of my sensors tested out

 

.41 ohms in the sensor ground circuit is okay. IAC would affect idle speed, not cause a miss. Have either of you ever snugged up your intake manifold bolts working from the center out with the engine cold?

 

Just torqued em. Could clogged exhaust do if?

 

Just wanna throw a thought out there..I have a bunch of small engines, water pump, gen, saws, ect, even a dozer...so I'm always playing with gas. (playing now as we speak)
It's a crap shoot on how much "blend" separates when, and with fuel from where. Always the 87...once in some from chevron I got 1/2 a gallon in a 5 overnight. Others will do over an inch in a 1 3/4 L bottle in a few weeks. LOOKS like water in a glass gar, but burns and kills Dandy-Lions!
Frustrating as some things will run with choke. Some won't start without Quick start then will run crappy. Sometimes all is fine.
I have here over a gallon of it I've gotten out of carbs and gas cans.

Leroy: "mine will start/run fine when its cold but as soon as it warms up and if i turn it off and back on, itll start misfiring." Exactly what mine did when sitting, the heat shield would absorb heat and expand, the front edge then grounding some injector wires. A supper easy check.

 

Leroy you think your exhaust could be clogged?