Running a bit rough

[-Lawless]

For those following along, I've replaced all filters, set timing and idle, and many many other things.
Car runs great at idle but over the last week or so I've been noticing the engine running really rough at about 2700 - 3200 rpm.
Mostly in 2nd and 3rd gear but can feel it in 4th and 5th as well at those RPM's.
It seems to be getting worse the more I drive it.

If I let off the gas it goes away.
If I push in the clutch, it goes away.
If I put it in neutral, it goes away.
If I am stopped in neutral, it doesn't shake at those RPM's

I think that tells me it's not in the drive line but more so in the engine, under load.

I've adjusted the IAC and timing a bit and saw no difference at all.
It almost feels like something is out of balance the way it shakes.

I'm going to look very carefully for any vacuum leaks tonight.
Any other ideas of things to look for?

[jtgh]

Why no mention of the CEL lamp?

Last fails like this was a bad fuel pump.

one guy , had his die at 3000 rpm , every time.

think in terms of load, the more load, the more fuel.
when cold the fuel demand is worse so it will fail at lower RPM.

it could be the EGR stuck open a tad ( or your exhaust is modified.)

are you running a stock system is this a modified car.?
custome anything or missing in the drive line. ?

custom exhaust, custom, intake cold air junk or missing smog components.???
sensors unplugged on the engine.

questions:
engine running really rough
does this mean loss of power, bogging or does it really shake?

Fuel pump will cause loss of power but not shake. (but depends on condition of engine)
AFR goes lean and bogs.
some weak engines with unbalanced compression can shake.
or if egr is stuck open (2 problems, nah never happen on a 89) hahahahah


forget gears and clutch.
think load.
now drive up a steep hill cold
now drive up a steep hill hot.

load the crud out of that engine. see what happens.

also
test WOT hot. wide open throttle, (specail ECU mode) EFI goes rich !

[-Lawless]

Originally Posted by jtgh

Why no mention of the CEL lamp?

Last fails like this was a bad fuel pump.

one guy , had his die at 3000 rpm , every time.

think in terms of load, the more load, the more fuel.
when cold the fuel demand is worse so it will fail at lower RPM.
After I get past 3200 rpm it smooths out a bit

it could be the EGR stuck open a tad ( or your exhaust is modified.)
I tested the EGR and it stumbles bad when I open it manually bu I'll check again that it isn't sticking open a little.

are you running a stock system is this a modified car.?
custom anything or missing in the drive line. ?
All stock

custom exhaust, custom, intake cold air junk or missing smog components.???
sensors unplugged on the engine.
Looked but didn't see anything unhooked

questions:
engine running really rough
does this mean loss of power, bogging or does it really shake?
It still has power, just shakes real bad. Can't see out of the rear view mirror when it starts shaking.

Fuel pump will cause loss of power but not shake. (but depends on condition of engine)
AFR goes lean and bogs.
some weak engines with unbalanced compression can shake.
or if egr is stuck open (2 problems, nah never happen on a 89) hahahahah


forget gears and clutch.
think load.
now drive up a steep hill cold
now drive up a steep hill hot.

load the crud out of that engine. see what happens.
Will give it a try.
also
test WOT hot. wide open throttle, (specail ECU mode) EFI goes rich !Is there any other way to drive? LOL!

See above

[jtgh]

best clue , cant see outside with mirror.. ooooo bad......



the CHECK engine lamp, is it on , at key On , NO start and does it go
out after starting.?


sounds like you are losing fire on 1 cylinder at certain speeds?

spark loss will be abbrupt , almost violent. like throwing a light switch.
as opposed to fuel loss taper off.

no MPI so no need to worry them. good news.

sure sounds like a candadate for compression test and a vacuum test.

you did many other thinks but did you do a full tune up?
rotor, cap, wires. and plugs. (gapped at 028" IIRC)?

[-Lawless]

Yep, full tune up including water pump, timing belt, adjusted rockers etc.
Ran really good for a month or so.
Only a code 12 so good to go there.

Last night I took off the IAC and EGR to clean. I thought I cleaned it the first time a few months ago but it appears I only cleaned the EGR valve and not the port to the manifold. Got that cleared out and it seems to run much better but still vibrates at higher speeds. No loss in power at all though. (That I can tell) It gets up to 75 mph with no problem, just vibrates. It does feel like a cylinder is missing by the vibration but it still has the power. Very strange....
I'll double check the plug wire connections again to make sure something isn't loose and giving me a weak spark at load.
I'll also do a compression test this weekend just to make sure.
Thanks Jerry for the suggestions.

[-Lawless]

Just for the heck of it, I'm going to run down to Autozone and pick up a new O2 sensor for $24.00 (Bosch)
It's going on 100k and is time for one anyway.

[jtgh]

$24 is a steal even for the hand wired one,
i have color codes if you need em.

compression test
vacuum test
engine mounts (1 bad , very bad like detached rubber bonds)


full power and shakes, that is hitting 9.5 on Will Smiths Wierdo meter......MIB. qoute.
A voodu dance might be needed soon.

[-Lawless]

oh no doubt on the weirdness meter.
I'm also the one with the seat belt light that likes to flash for no reason

Ya Here is the link for Autozone.
AutoZone.com | Shopping | Parts | Product Detail - Oxygen Sensor

Hope it is the right one...

The OE type is $39.00

[jtgh]

yah yours is the old fashioned 1 wire sensor.

way dirt cheap they are. ,no heater.

[-Lawless]

Ok the problem turned out to be a bad universal joint. lol

go figure....