slight popping maybe misfire at idle

[mitsustar86]

My car is making a slight popping noise at idle sometimes it does it sometimes it does not. Its usuualy when I start it after is warmed up. Any ideas? Plugs, wires maybe tps?

[mistapickles]

headgasket...

[Starfighterpilot]

How does the engine perform other than the popping @ idle?

 

What Is your idle RPM?

 

For What It's Worth.

 

KEN

[mitsustar86]

I just replaced head gasket. My idle is at 900. Sometimes when I start it it will drop to 600. It runs fine. Under boist at wot it cuts out a little but I think that's a fuel/tune issue. One thing i haven't do is fuel filters.

[Shelby]

cracked or split power brake booster hose,, or any vacuum hose off any where on the intake or device that uses one

[mitsustar86]

My booster vac line got crusty and broke one day so I bought a new one but its slightly bigger so I might neef to get adjustable clamps for it.

[Starfighterpilot]

My booster vac line got crusty and broke one day so I bought a new one but its slightly bigger so I might neef to get adjustable clamps for it.

 

 

Well I think you may have found your problem with that hose. It must be tight around it's attachment metal piping nipples/ridges.

 

In addition, check ALL of the turbo to intercooler to TB hoses for long cracks inside of the hose ends and make sure that all of the hose clamps are tight. I'd also check the turbo intake accordian hose for cracks or holes and that it's hose clamps are tight and the rubber collar insert for attaching the accordian hose to the inlet to the turbo is properly seated inside of the hose.

 

" Under boist at wot it cuts out a little but I think that's a fuel/tune issue."

 

If you are getting a slight cutting out at WOT in addition to popping at idle, you my have a slightly weeping/dirty secondary fuel injector. Here is how you check the injectors for weepage to see if one or both are leaking or weeping gas: Remove the metal pipe that is going across the top of the engine valve cover to the throttle body. Get a clean rag and stuff it down the throttle body air inlet bore. Get a long wire and use it as a jumper between the positive pole of the battery and the fuel pump electrical test connection which is located in the engine compartment by the air filter canister. Using this jumper, energize the fuel pump for about a minute or so. Then remove the rag from the throttle body to see if there is ANY evidence of gas on it. If the rag is dry you are home free. If there is gas on the rag, then energize the fuel pump again for a minute or so, and, using a flashlight look down the throttle body bore to see if you can see which injector is weeping gas. Can't see it? Then put your finger on the tip of each injector to see if you get gas on your finger. You must either replace the weeping/leaking injector (probably the seconday) or you clean it or have it cleaned.

 

 

It may be a good idea to just send your injectors out to be tested and cleaned. In most cases, God only knows when they have been cleaned the last time.

 

For What It's Worth.

 

KEN

 

Another brain fart - what is your idle RPM at cold start up? If it's not about 1500, gradually decreasing to about 900, as the engine warms up, you may have a dirty/corroded the ISC nose switch which causes the engine to run rich when the engine is at normal operating temperature. Check your error codes to see if you have any. If so take the appropriate steps to correct the error code IAW the FSM Chapter 14.

 

Have you checked your engine coolant temperature sensor IAW the FSM to verify that it's operating correctly?

[Speedy2222]

 

Another brain fart - what is your idle RPM at cold start up? If it's not about 1500, gradually decreasing to about 900, as the engine warms up, you may have a dirty/corroded the ISC nose switch which causes the engine to run rich when the engine is at normal operating temperature. Check your error codes to see if you have any. If so take the appropriate steps to correct the error code IAW the FSM Chapter 14.

 

Have you checked your engine coolant temperature sensor IAW the FSM to verify that it's operating correctly?

 

you know my car started doing that last week. when it is cold runs just fine but as it heats up it starts popping at idle. knock sensor has been kicking in alot earlier than it use to also. no CEL or anything. i figured timing may be a little off or i had a bad plug or something. car runs fine anywhere but idle.

[Starfighterpilot]

you know my car started doing that last week. when it is cold runs just fine but as it heats up it starts popping at idle.

 

Your Starquest started doing WHAT last week?

 

What is your stone cold idle RPM and warmed up RPM. Answer the questions previously asked or we can't help you!

 

 

knock sensor has been kicking in alot earlier than it use to also. no CEL or anything. i figured timing may be a little off or i had a bad plug or something. car runs fine anywhere but idle.

 

The knock sensor should never be "kicking in" unless you are running regular gas @/WOT or your engine's timing is way off.

 

I strongly suggest that you down load the Starquest FSM and start reading and understanding it. After you read it there is nothing wrong in asking for clarification of a particular point that you don't completely understand or have questions about.

 

For What It's Worth.

 

KEN

[Speedy2222]

Stone cold it jumps up to around 1400 or so. After its warm id say its around 900 its a full needle under 1000. My knockbox kickin in is due to boost being turned up. It usually knocks at around 18lbs but if i am in 3rd and roll into it itll do it at 3000 rpm and about 14lbs

[Speedy2222]

I forgot to add it is missing at idle is what it started doing

[Starfighterpilot]

As Shelby suggested in his post above, check all of your vacuum lines for rips, cracks or holes. I'd especially check your tubing to the vcacuum advance. Also pull the distributor cap and suck on it's vacuum line. Does the vacuum advance arm smoothly retract? If not then the vac adv is shot. Keep your tongue on the end of the tubbing after you sucked on it - does the arm slowly retract? If so, then the vac adv is shot. Take your tongue off of the tubing end - does the vacuum adv arm smoothly retract? If not then there is a problem in either the vac adv assembly or the internals of your distribuitor.

 

Did the popping start after you replaced the brake booster tubing with the oversized ID tubing? If so you found your problem.

 

Are all of the gang of three vacuum tubing to the intake manifold nipples under the TB hooked up correctly? See the appropriate FAQ for the correct configuration. These vac lines have a habit of blowing off - especially considering the amount of boost you say that you are running. It's best to zip tie them to the intake manifold nipples so they stay on.

 

For What It's Worth.

 

KEN

[Speedy2222]

Vac advance is less than a year old but can sti check it. All hoses are oem( most were replaced less than a year ago). Alll are hooked up correctly at TB

[Starfighterpilot]

Have you checked the O₂ sensor IAW the FSM to ensure it's operating correctly?

 

Have you run a set of error codes?

 

If you don't have any error codes then replace the oversized vacuum line to the brake booster, cuz it's leaking air into the intake manifold causing the warmed up engine intake manifold air flow to be running lean and upsetting the correct air/fuel flow in the intake manifold which could be a source of your warmed up engine "popping" problem.

 

Remember that the EFI ECU runs the cold engine rich until the CTS tells the EFI ECU that the engine is warmed up. Then fuel is metered through the injectors in the correct proportion for the air flow signal coming from the AFS.

 

For What It's Worth.

 

KEN