Sliding

I've noticed that sometimes car doesn't pull like it should.
It looks like one cylinder sometimes work normally and sometimes not.
This is hapening only when car is warm, when cold everything is O.K.

Last month I've ported plunum, runners and intake base and I have cleaned
TB. Could this be related?
But I think that this have happened before but not so often.

Could spark plugs be the problem?
I have AC FR5LS spark plugs. Are these O.K. for L98?
Would You recomend any other spark plugs?

I have also noticed that when I start car idle jumps too high and it falls back
to normal slower than before. I've been reading something about reseting IAC
after cleaning TB. What actually is IAC and how can I reset it?

Thanks!
:chevy

Rich B.

FR5LS is the correct plug for your L98. But how do they look?

Is your timing @ 6* BTDC?...How's the distributor cap (inside) look? Any "tracking"?...Wires clean & dry; no bulges?

Looking at your location, I'd be inclined to say "poor gas quality"...(diluted with methanol, maybe?)...

There is at least one (more like several) thread on IAC setting, in the Archives...

...heh...Here's one, from the next post on the list... http://www.geocities.com/jgkov/index.html


[Modified by Rich B., 10:50 AM 4/14/2002]

Sliding

Spark plugs look good.
I didn't think about gas but I see your point.
Several of my friends have complained about gas quality.
Wires are almost new ( bought a year ago ).
I will check on distributor cap.

I will try with fuel aditive and see if there will be any diference.
I'm going to try that now and will be back with results.
Thanks.


[Modified by Sliding, 12:02 PM 5/4/2002]

Rich B.

You didn't mention any knocking or pinging, but if the ECM/knock sensor detects knock, the ECM will retard the timing to compensate...

that will definately affect performance...

So it works OK in Open Loop, but when it goes into Closed Loop, the sensors are detecting something has failed/or is out of normal operating range (or is causing detonation)...

...Ugh...Is it setting a code? Any error messages?

BTW: I've been told that those octane boosters can ruin catalytic converters and/or oxygen sensors...


[Modified by Rich B., 2:34 PM 4/14/2002]

Sliding

No error messages so far.

I was driving the car for last half hour and it worked fine.

As I said before sometimes engine works good and throttle response is
excellent even when engine is hot, but sometimes I can feel that when I
push pedal a little bit harder there is some hesitation. It feels like something
is wrong with timing or like one cylinder is not working.

Rich B.

Carry a bent paper clip with you...When car starts acting up, put it in the A & B holes of ALDL...This is "Diagnostic Mode", which is also Open Loop...See if problem goes away...

If it does, you have to start figuring out which sensor is acting up...

Togo

are you getting any backfiring through the TB?
i too experience this problem, but am experiencing backfiring while revving up. i have pointed it to 2 problems, one i know for sure is the spark plugs or wires.....i have oil in 2 cylinders so i lose 2 plugs every couple months, or the wires get too hot (don't ask) and don't fire properly. the other problem i have noticed is the problem got worse when i tried a friends MAF (he thought it was bad, and it looks like it is) so i have some work to do myself....the first thing is to REPLACE MY motor!!!!!!!
another way you can see if all plugs are firing is to get one of those thermometers (laser i think) and see the temp of the cylinders....if one is not firing, it should be considerably cooler than those that are!

good luck with yours!


[Modified by 85_togo, 3:34 PM 4/14/2002]


[Modified by 85_togo, 3:36 PM 4/14/2002]

Sliding

[QUOTE]Carry a bent paper clip with you...When car starts acting up, put it in the A & B holes of ALDL...[QUOTE]

Do You mean that I should shorten pins A & B ?

Sorry but I'm not sure what do you mean by paper clip.


[Modified by Sliding, 11:44 PM 4/14/2002]

Sliding

No backfire from TB.

Spark plugs are all dry and look good.

I'm only not sure how big should be space between electrodes on spark plug.
Usually on European cars it's like 0.6 mm and on mine is 0.9mm.
Is this OK?

Togo

i don't know what the metric conversion is, but i believe i gap mine at 35 thousandths anybody else know for sure????? (and NO i don't expect anyone else to know what i gap MY plugs at :lol:)

Sliding

0.9mm = 0.035 inch

Rich B.

Yes, short out A & B, this puts ECM in diagnostic mode. Do it from dead engine (from "Off"); insert paper clip (or conductive wire jumper); make sure key is turned to "Run" position but engine not started... (If any codes are set, you will see flashing of SES light...1 flash, then a pause, then 2 flashes...That's read as "12"...It will flash that 3 times, then it will flash any error code 3 times, then finish up with flashing "12" 3 times again...)

Anyway, make sure you do it with engine off, then switch on and run it...

...Did that make sense???... :crazy:

Sliding

O.K.
I will try this probably tomorrow.
I will let you know what happened.

Thanks for all the help.

Sliding

Rich B., I did as you told me.
I get "12", "12", "12", "12"... and so on.
Is this error code 12 or no error code?

Today I took down TB, disassembled IAC motor, cleaned it and put
everything back together.
Also I've done TB bypass.

Car is working better now, but the problem is still the same.
When engine is hot, it's not working good.
I'm running out of patience. I think it's time to use :smash:

92LT1Roadster

1. Have you checked to see if all you fuel injectors are firing properly. (flooding or firing Intermittingly)
2. I also do not trust spark plug wires to perform for years on end with my foot on the pedal. You stated that your sare 1 year old, but with pulling the wires over and over by checking your spark plug you damaged one?? or maybe it is hitting the manifold and losing spark to detonation of that metal ... this is possible. (My car was losing power because a wire welded itself against the hot manifold. I did not know what the issue was. After I found the issue I was really glad... Check those wires and I actually suggest changing them. They are 1 year old, it would'nt hurt.

Rich B.

That means no error code is being set...That's good!

Could be wire as suggested above...Or bad spark plug...(Champion plugs come with one bad plug in every set of 8...)

Do you have induction timing light that you can use to see which cylinder is misfiring? Try a new wire and/or plug in that cylinder and see if it cures it...

Sliding

Things are getting worse.
Car now coughs even when it's not warmed up.
I'm begining to think that maybe fuel pressure is not good.
I took down all spark plugs and they all look the same.
Shouldn't one be wet or dirty if only one is defective?! :confused:
Next week I'll try to find fuel pressure gauge to see what pressure am I getting.
What should be stock fuel pressure.
Maybe fuel filter is bad. I'm planing to change it anyway.
What do You think?

ittlfly

Checking the fuel pressure at this point is a good idea. poor pressure will indicate a problem with the pump, fuel filter, regulator or clogged fuel line. If the pressure is good, then do a leak down test on the injectors to see if you've got a bad one. At least it will give you some direction rather than just throwing parts at it.


[Modified by ittlfly, 10:30 AM 4/28/2002]

Sliding

Can I drive the car in diagnostic mode???

BBA

At night, open the hood, disconnect the hood lights and look at the spark plug wires with the engine running. A bad spark plug wire will glow in darkness.

I suggest taking your distributor cap off, removing the coil and testing it for correct resistances across it's windings.