Low idle sometimes stalls

[BOB F]

This is a new problem. Sometimes on startup with a bit of gas it will start fine then just fro off and die. Starts right back up

Sometimes at a light it will just die.

Sometimes idle is like 400 rpm. Other times 650.

Any thoughts? Thank you

 

[DirtDawg]

Well it's clear that you need to get that idle back up. So let's think, what causes the engine to run at a lower rpm?
-Dirty throttle body
-Dirty MAF
-Clogged fuel filter

So I would start by cleaning the throttle body (you will be surprised how dirty it is), clean the MAF, disconnect the battery for 30 mins, then see if that helps the low rpm. If it is still a little low you can perform a seafoam Treatment &a gas system Treatment (most on here including me prefer 44k).

I would do that first, then if the problem still persists we can further diagnose.

 

[2001LC]

What year, how many miles, who's been maintaining & how often, mods etc.

 

[BOB F]

Well it's clear that you need to get that idle back up. So let's think, what causes the engine to run at a lower rpm?
-Dirty throttle body
-Dirty MAF
-Clogged fuel filter

So I would start by cleaning the throttle body (you will be surprised how dirty it is), clean the MAF, disconnect the battery for 30 mins, then see if that helps the low rpm. If it is still a little low you can perform a seafoam Treatment &a gas system Treatment (most on here including me prefer 44k).

I would do that first, then if the problem still persists we can further diagnose.

Great thank you.

Where is the fuel filter?

 

[BOB F]

What year, how many miles, who's been maintaining & how often, mods etc.

1998. 175k miles. Original owner

Not a lot of maintainence other than regular oil changes. It hasn't needed much in all these years.

I just soldered a new fuse holder only the efi fuse location.

 

[2001LC]

1998. 175k miles. Original owner

Not a lot of maintainence other than regular oil changes. It hasn't needed much in all these years.

I just soldered a new fuse holder only the efi fuse location.

Air filter ever 20K right?
Battery post clean & greased (baking soda solution) and in good condition?
Fuse holder for what? You mean you tap into that location? When was this done?

Before we start looking, good PM stuff like @DirtDawg suggest or gas cap kind of stuff, it's good to get accurate picture of state of your rig.

 

[ton504]

1998. 175k miles. Original owner

Not a lot of maintainence other than regular oil changes. It hasn't needed much in all these years.

I just soldered a new fuse holder only the efi fuse location.

Did you disconnect the battery?

If so disconnect the battery again. Clean your throttle body and plate. Then reconnect the battery.

 

[BOB F]

Air filter ever 20K right?
Battery post clean & greased (baking soda solution) and in good condition?
Fuse holder for what? You mean you tap into that location? When was this done?

Before we start looking good PM stuff like @DirtDawg suggest or gas cap kind of stuff, it's good to get accurate picture of state of your rig.

I have a new air filter here. I'll install tomorrow.

New battery. I just had the battery out doing the fuse repair.

Efi fuse issue. Not a tap but a replacement of that mini fuse with the larger type fuse in a waterproof holder. I'll post a pic if desired. That fix for the efi fuse issue has been discussed on here.

 

[BOB F]

Did you disconnect the battery?

If so disconnect the battery again. Clean your throttle body and plate. Then reconnect the battery.

The battery was just disconnected doing the fuse repair. Maybe the ecu isn't up to speed yet? I'll
Drive around a bit.

I'll clean the TB.

Thanks

 

[ton504]

The battery was just disconnected doing the fuse repair. Maybe the ecu isn't up to speed yet? I'll
Drive around a bit.

I'll clean the TB.

Thanks

I guess I should have elaborated more. Over time the ecu adjusts the throttle plate position to meet the target idle rpm. As the throttle body/plate gets dirty, the ecu will adjust its position to maintain the target idle rpm. Since you disconnected the battery, the position is now lost and resets. If you continue to drive it like so, it will adjust. But I prefer to clean it and start off fresh.

 

[BOB F]

I guess I should have elaborated more. Over time the ecu adjusts the throttle plate position to meet the target idle rpm. As the throttle body/plate gets dirty, the ecu will adjust its position to maintain the target idle rpm. Since you disconnected the battery, the position is now lost and resets. If you continue to drive it like so, it will adjust. But I prefer to clean it and start off fresh.

I understand the ecu learning process. I will freshen up the TB. I just put in a new air filter. The old one was like new though.

I hadn't drove it after the fuse repair. I just my wife it's fixed and she came in and said it wouldn't stay running. Maybe the issue is as a result of the ecu reboot?

 

[2001LC]

ECU adjusting won't normal cause this issue, at least not so severe.

Tune up as suggested above, but disconnecting battery first cleaning & greasing post. Don't reconnect battery until done, and only use MAF cleaner on MAF. While at parts store getting MAF cleaner have them test your gas cap.

My concern here is the EFI fuse. I say this because anythime something is worked on, then suddenly issue after a repair, it's the first place I look.

 

[BOB F]

ECU adjusting won't normal cause this issue, at least not so severe.

Tune up as suggested above, but disconnecting battery first cleaning & greasing post. Don't reconnect battery until done, and only use MAF cleaner on MAF. While at parts store getting MAF cleaner have them test your gas cap.

My concern here is the EFI fuse. I say this because anythime something is worked on, then suddenly issue after a repair, it's the first place I look.

 

[BOB F]

Will do.

This is the fuse fix. Other than battery DC I don't think it is a contributing factor.

 

[2001LC]

Link me to thread so I read why you did this.

My first thought is intermittent short, possible from vibration. This would cause fuel pressure to fluctuate. It looks good but them can't see the underside, something went wrong to prompt this mod.

 

[BOB F]

Link me to thread so I read why you did this.

My first thought is intermittent short, possible from vibration. This would cause fuel pressure to fluctuate. It looks good but them can't see the underside, something went wrong to prompt this mod.

My immobilizer fix

 

[BOB F]

Link me to thread so I read why you did this.

My first thought is intermittent short, possible from vibration. This would cause fuel pressure to fluctuate. It looks good but them can't see the underside, something went wrong to prompt this mod.

fix for immobilizer issue?

 

[2001LC]

Ok, I've read that thread. You never stated much about condition that prompted your EFI jumper. IIRC your wife knew to wiggle fuses relays to get started. So I assume you had a no start condition perhaps immobilizer light blinking ignition on IDK.

As stated above do the tune-up (44K, TB, MAF, Air filter, battery 30min disconnect clean & grease post, check all vacuum lines & PCV valve, inspect & clean spark plug (do not change gap of used plugs)) goes a long way here. I add using dialectic grease on coil to spark plug ends & MAF sensor connecting wires pins (not sensor wire) is good practice as well.

But it's very possible your issue is related to reason you did EFI fuse jump. I've not had to deal with this issue, fortunately. I agree with some that it's a great idea, but a temporary fix. A new fuse box is most likely in order in, at some point. Could be the fix, but for now run through some basic stuff. One being fuel pressure.

A/F (Air/fuel) mixture is most common reason for rough or low idle. As you're no doubt aware there is a number of things that can effect A/F. Two main cause of fuel pressure issue:

1) Bad gas clogging up system, anywhere from fuel pick filter to injector jets. This is most often associate with the "D" vibration (rough ideal in D with foot on brake, causes a vibration sound and low idle). A can of 44K in tank, along with above tune-up goes a long way.

2) Fuel pump. Fuel pressure gauge is handy here. A quick test is to pinch off return pressure line hose (hung on clip at rear of plastic engine cover, DS) while condition exist. This "backs ups" pressure in fuel system, developing a little extra pressure. If fuel pump is weak, idle may respond (pick up). In your case, with "intermit issue" it may be useless, but worth a try. I say this because fuel pump may be getting reduce current running weak, or may have current cutting in or out. Not knowing more about your EFI mod reason. I'd add; Bad fuel pump may have been issue all along or going bad at same time of fuse box issue.

Fuel pressure may have nothing to do with your issue but well worth checking.

Anyway that you can monitor fuel pressure and/or A/F while running, like with tech stream would be helpful as well.

Eliminate or confirm fuel pressure issue, then move up the food chain to intake air then spark.

Good luck!.

Note: Fuel pumps weaken over time. Running fuel tank down after low fuel light has come, on reduce life. Pump submerged in fuel keeps it cool.

 

[BOB F]

Ok, I've read that thread. You never stated much about condition that prompted your EFI jumper. IIRC your wife knew to wiggle fuses relays to get started. So I assume you had a no start condition perhaps immobilizer light blinking ignition on IDK.

As stated above do the tune-up (44K, TB, MAF, Air filter, battery 30min disconnect clean & grease post, check all vacuum lines & PCV valve, inspect & clean spark plug (do not change gap of used plugs)) goes a long way here. I add using dialectic grease on coil to spark plug ends & MAF sensor connecting wires pins (not sensor wire) is good practice as well.

But it's very possible your issue is related to reason you did EFI fuse jump. I've not had to deal with this issue, fortunately. I agree with some that it's a great idea, but a tempera fix. A new fuse box is most likely in order in, at some point. Could be the fix, but for now run through some basic stuff. One being fuel pressure.

A/F (Air/fuel) mixture is most common reason for rough or low idle. As you're no doubt aware there is a number of things that can effect A/F. Two main cause of fuel pressure issue:

1) Bad gas clogging up system, anywhere from fuel pick filter to injector jets. This is most often associate with the "D" vibration (rough ideal in D with foot on brake, causes a vibration sound and low idle). A can of 44K in tank, along with above tune-up goes a long way.

2) Fuel pump. Fuel pressure gauge is handy here. A quick test is to pinch off return pressure line hose (hung on clip at rear of plastic engine cover, DS) while condition exist. This "backs ups" pressure in fuel system, developing a little extra pressure. If fuel pump is weak, idle may respond (pick up). In your case, with "intermit issue" it may be useless, but worth a try. I say this because fuel pump may be getting reduce current running weak, or may have current cutting in or out. Not knowing more about your EFI mod reason. I'd add; Bad fuel pump may have been issue all along or going bad at same time of fuse box issue.

Fuel pressure may have nothing to do with your issue but well worth checking.

Anyway that you can monitor fuel pressure and/or A/F while running, like with tech stream would be helpful as well.

Eliminate or confirm fuel pressure issue, then move up the food chain to intake air then spark.

Good luck!.

Note: Fuel pumps weakens over time. Running fuel tank down after low fuel light has come, on reduce life. Pump submerged in fuel keeps it cool.

Thank you for the detailed reply.

I am pretty confident that the no start issue I had was related to the known efi fuse problem as the cure for it was wiggle and reinsert that fuse. This occurred fairly often and lately more frequently. Since the fuse repair the other day, the car has not been used much.

Before I did the fuse repair, it dropped idle at a red light and died. It started right up again. I think this idle issue was there before the fuse fix. As I said , right now it seems ok but I'm wary.

I wanted to check the fuel filter. Where is it ?

I'll get into cleaning the MAF, etc as well


Thanks again

 

[2001LC]