roughs idle

Is the MIL indicating and have you tried to retrieve for trouble codes?
Symptom indicates a possible misfiring cylinder.
Was the distributor in anyway adjusted? Have you checked the distributer with crank sync?
Was any repair to engine components made prior to this occurring?

no check engine ligh is not on. this vehicle does not have a distributor its a diesel engine not a gas.all filters have been changed

Sorry, it should have been the injection pump timing.
Did you test if any cylinders i snot firing correctly?

Try cracking the injector line cylinder by cylinder to check if any is not functioning correctly.

Already tried that all 8 inj have been replaced and when I remove injectors like you say it make a little difference but engine still rough and smoking but when I accelerate it goes away but smoke still present. Smoke is white

Performing the above does not necessarily mean to check for faulty injectors. It is to locate any cylinder that is not firing correctly. It could be a fault with compression.

Did all cylinder shows similar amount of difference in engine running condition or did any one or more showed a more significant difference?

Do you have coolant losses issues and did engine ever overheated badly?

White smoke is usually due to non firing conditions or timing is too advanced. It could also mean a minimal amount of water is getting to the cylinders, either due to a bad head gasket or bad cylinder head.

99 Blazer 130,000miles 4.3L V-6

I have been beating my head against the wall on this one. Over the course of the past few days I have dumped just over $300 dollars into parts and nothing has changed. No Codes other than a P0452 Evap low code(been getting this one for a while, but hasn't created any drivability problems.) The problem started while I was driving. The truck would run fine down the road then when I let off the gas to stop it would die. It always starts right back up. In two days it went from dying a couple times, to dying everytime I stop. I have replaced the IAC, EGR, and the MAP sensor, problem worse now. Used a fuel pressure gauge on the fuel system and pressures are good. Used a scan tool to check other systems, MAF, IAT, TPS, etc, everything looks good. Heres the odd thing though. The new MAP sensor is giving some really strange numbers, same thing the old one did. Haynes book says 1.5-2volts at idle and 4.5 full throttle, I get 1.70v at idle. As I depress the gas pedal, the voltage goes down, not up. The more pedal I give it the more the voltage goes down, never higher than 1.0 volt and as low as .5volt. I'm going to try to swap out the new MAP sensor for another new one and see if I happened to get a bad MAP sensor, but the old one acted the same way. I have no idea what to look at next. PCM??? I have replaced all plugs and wires, cap and rotor, and the fuel pump within the last year. Put a new MAF on it about 2 years ago.
Any help would be greatly appreciated.

[quote:ef5d9ed8ee="myles"]I Have a 1994 Acura Legend L with 74,000 org miles. lA couple of weeks ago the speedometer would stop indicating then fiix itself, finally last night the speedometer stopped working altogether and the D4 began flashing on the shift indicator. I did sometimes notice a slight burning smellbut only for a second. No other problems with the car. Any help you guys could giive me would be appreciated.[/quote:ef5d9ed8ee]

Check your vehicle speed sensor

Hello, I have had this truck for 5 years with no problem. A friend borrowed truck to haul equipment 1000 miles away. When he brought it back, he said it will not idle and would barely stay running. (nice friend). So here I am with a problem. I changed all plugs, wires and rotor. Flushed radiator, changed oil, oil filter, new power steering fluid, new brake fluid, and cleaned air filter. I pulled off intake and sprayed carb cleaner. I added marvel mystery to gas and filled tank up. With all that being done, it still has a rough idle around 400 on RPM gauge. Oil gauge fluctuates around 40. Headlights are dim, but when accelerator is pressed they go bright again. I definitely here a ticking under the hood. Fuel module in gas tank was replaced around 6000 miles ago. I also replaced the fuel filter about a month ago. Please help, I am confused..could it be IAC, MAF or what?

Is the ses like on, when your having the problem? Have the codes checked, some of the national brand autostores will check codes for free if you can get the vehicle down there. If there is a misfire code, it might tell you which cylinder/s is having the problem.

If you think the problem is a fuel issue, start by checking the fuel pressure. I don't care if everything is brand new, I'd still check fuel pressure.

As far as the fuel issue, if you have the csfi fuel system, there are bulletins about cleaning the fuel poppets. That is a shop procedure, I don't think pouring stuff in the tank will help

This is the CSFI vehicle. The SES light does stay on all the time (3+ years now). I am a girl however I love to work on this thing. So should I go ahead and take the intake off and get started on the poppets? Would this make the truck have a missing sound almost like a tappet sound? The belt definitely needs to be changed.

The po300 code can be awkward to track down, I sent you a private message, I don't know if you received it? goodluck

1998 Chevy Truck Rough idle OBD Code P0300-Random Misfire normally results from vacuum leaks or bad fuel

Misfiring can be caused by worn or fouled spark plugs, a weak spark (weak coil, bad spark plug wire), loss of compression, vacuum leaks, anything that causes an unusually lean fuel mixture (lean misfire), an EGR valve that is stuck open, dirty fuel injectors, low fuel pressure, or even bad fuel

i recently changed motors i have a 1998 chevy ext cab 5 speed well ichanged it to a 700r turbo automatic and put a motor out of a 2002 gmc sierra 1500 well i putit all together now it idles rough when u give it gas it dies i put it on computer and it gave code po118 n po115 help please

You have a problem with the coolant temp sensor circuit. Double check the wiring and make sure none of the pins got bent over or the wires aren't frayed at the connector.

MY 1997 with 133,000 miles chevy pick up has a rough idle. After the vehicle warms up and it starts about 30 seconds after comming to a stop. I put new plugs in and it seemed to help a little but has not solved the problem. Any suggestions would be greatly appreciated.

[quote:09335a0944="Garthr"]MY 1997 with 133,000 miles chevy pick up has a rough idle. After the vehicle warms up and it starts about 30 seconds after comming to a stop. I put new plugs in and it seemed to help a little but has not solved the problem. Any suggestions would be greatly appreciated.[/quote:09335a0944]

Hey garth,
By chance is the check engine light on or flashing? You may also need to complete your tune up w/ a dist cap/rotor and wire set (if installed) Let me know!

Chris

Chris, old plugs looked good. Dist, wires & rotor changed @ 75000. Think maybe Oxygen sensor? Check engine light stays on for days and then goes off for a day or 2.

[quote:70c2e89a30="Garthr"]Chris, old plugs looked good. Dist, wires & rotor changed @ 75000. Think maybe Oxygen sensor? Check engine light stays on for days and then goes off for a day or 2.[/quote:70c2e89a30]

Garth,
I would recommend 1. finish the tune, cap/rotor/wireset as its close to the recommended time frame. 2. get the truck scanned for codes and get back to me with the codes and code descriptions. Let me know!

Chris

Have changed plugs, wires, aic valve, egr valve, cleaned mass airflow sensor and throttle body. Still Idles very rough and a lot worse when in gear. Much better when accelerating. Please help.

Hello,

Ok, unless you forgot to mention it you didn't replace the Distributor Cap & Rotor...

I would remove the cap and take a look inside if the electrodes are corroded or worn down replace both.

Thanks for the reply. Changed the cap and rotor and truck idles much better. However after it warms up, while still idling much better, the rpms go down and i can hear the occassional ping again. Anything else you might recommend.

Ok, is engine light on? if so could be the Knock Sensor, it is suppose to control the ping...


The knock sensor is located on the engine block, cylinder head or intake manifold. This is because the function of this sensor is to sense vibrations caused by engine knock. The PCM uses this signal to alter the ignition timing and prevent detonation. It will compare this information with its preset tables to identify an engine knock or ping. If a ping is sensed it will retard the timing to protect the engine from this damaging pre-ignition.

The knock sensor is a piezoelectric sensor that contains a piezoelectric sensing crystal and a resister. This crystal creates a small amount of voltage when shaken. This sensor takes advantage of this unique property.

Symptoms: The symptoms of a bad knock sensor usually show up at highway speeds or under a load. Be clear that this sensor effects the ignition timing of an engine. The vehicle will have a loss in fuel mileage and acceleration especially at highway speeds. The customer may complain that the vehicle's engine doesn't feel right. Some COP coil on plug systems use strategies that cancel cylinders, see the manufacturer's manual for special instructions. Some of these are located on the cylinder heads under the intake manifold. The vehicle's computer will detect a bad knock sensor, set off a code (P0325-P0332), and enter fail safe mode.

KS Location

On left side of engine block, below exhaust manifold, forward of starter.


Other cause could be low Octane you could try adding an Octane Booster to see if clears it up.

Question - Has anyone mess with the distributor, remove the hold down bolt or removed the distributor?

Recently, I drove my truck from NYC to VA. When I stop for gas I noticed It was idling rough. So I thought that may it was from bad gas, so I filled up when the tank was alomost empty with super gas. When I was back in NYC I had may oiled change because it was time. After that while driving the car cut off and would start. It was the fuel pump, so I change it. The car is still idling rough with check engine light flashing when stop and staying on while moving.
The shop told me there wasn't enough presure in one of the cylinder and that I would need a new engine soon. So the tech said it maybe a carbon buildup and put some stuff that a Gm tech said try and added techron cleaner to the fuel tank. He said drive it around for a while and see what happens. The truck seems too still have the pick and power. Should I do this or just start with a tune and so on?

okay fist things first, change the air filter, then the spark plugs and wires, since its a newer make youv'e probally got direct ignition ( no distributor), then drain the oil out, even if you got a change yesterday, but drain it out then add oil keep her idling for 10 - 15 min, the drain, and add oil, then you sould be good to go, if not let meknow

Thanks for your reply. The check engine light does not come on. Actually drives much better when driving on highway and does not have the ping. Could it be caused by carbon build up and, if so what is the best product to uze.

Oh sorry. Nobody has messed with the distributor.

I use SeaFoam pic attached, also check the vid on use...

http://www.youtube.com/watch?v=vRAV5ln5cUc

Thank you.

No problem... If you would once you are Satisfied with results please click on the User Satisfied button at bottom.

I have a 96 chevy 4.3 vortec with multiple misfire. It idles rough and when i apply the brakes the taillights flicker.What would cause this?

Check the charging system and ground circuits. The flickering taillights seems to indicate the above and low battery voltages can cause misfiring and other issues.

I have a 96 chevy c 1500, 5.7ltr. auto., 2wd, my check engine light is on and the codes are po300, and po305, it is idleing rough and it has a distinct miss comming out of the right (pass. side) tailpipe. any hints as to what this might be?

P0300 random misfire code usually indicates a vacuum leak or bad fuel.

P0305 is a misfire in cylinder number five should lead you to check the spark plug, fuel injector and compression.

Misfires can be caused by worn or fouled spark plugs, a weak spark (weak coil, bad spark plug wire), loss of compression, vacuum leaks, anything that causes an unusually lean fuel mixture (lean misfire), an EGR valve that is stuck open, dirty fuel injectors, low fuel pressure, or even bad fuel.