Car Q: accelerates for 2-3 seconds at a time then dies

I have a 98 mk3 Jetta GL, 2.0 i4. When driving it starts and idles fine, and when I press the gas it accelerates normally for about 3 sends then dies. Dies like the fuel shut off - no electrical dimming or anything like that. If I keep my foot on the gas it doesn't recover, but if I take my foot off the gas and press it again, I get another 3 seconds before it dies again. This happened while driving home and I was able to make it several miles back just by pressing the gas 2-3 seconds at a time, on then off, and it drove almost normally, able to maintain full speeds etc.

Error codes only indicate bad O2 sensor, this has been an issue for months. The cat crumbled and blew out last year, a shop welded in a new cat but couldn't remove the seized front O2 sensor. I suspect the welding fried the components and the O2 sensor failed, but after completely disconnecting the O2 sensor it ran just fine, presumably reverting to factory defaults while the O2 was blind.

The current issue began not long after sitting for months not driving (Covid shutdown I didn't drive anywhere). The battery had gotten fully dead, and after recharging, it ran fine for most of a few days before this arose. possibly the dead battery lost the saved fuel map? Seems to possibly line up with the battery not charging also -

I assumed it might be battery or alternator, but runs exactly the same with a good full battery from my other car, and alternator appears to put out full voltage...

thoughts?

Re: Car Q: accelerates for 2-3 seconds at a time then dies

Dirty30 Dillon /

I honestly can't foresee a dead battery losing factory coded data.

I do know that electrical issues abound in that era, but I just thought they were more common in the peripheral systems vs. engine management.

Apparently there is an immobilzer circuit in the system that kills the car before it can take off, and it's possible there is a chip/wafer in the key that signals all-ok.

Potentially look into that, or your ECU is simply bunk.

Re: Car Q: accelerates for 2-3 seconds at a time then dies

Sounds like when it comes off the cold start valve and into closed loop it shuts off the fuel pressure. My money is on o2 sensor, there might be 2 on your car. I’ve never had an mk3 but I have had many a car with cis-e and most of the time it’s either the thermo time switch or the o2 sensor

Re: Car Q: accelerates for 2-3 seconds at a time then dies

Going to say O2 as well, but so many things, the ability to "fume" it with pumping the pedal is really odd, never been able to do that with an injected car....get it going and trade it in on a Yaris and forget about cars forever! :) Best of luck!

Re: Car Q: accelerates for 2-3 seconds at a time then dies

Since being in Germany, I’ve owned two VWs and a BMW motorcycle.

I am convinced that “German engineering” is a type of Rube Goldberg machine put together with tools/fasteners that don’t exists; except for in the German factories and service shops.

They look like normal vehicles. But it’s just a facade.

I think your first post said something possible. Not getting fuel. If pressure is too low, it may cut off. Or a clogged return line doing something wonky to the pressure. O2 sensors should just kick you back to safe mix. But “German engineers” may have their O2 sensors sample every 1.5 seconds and only shut down throttle if two sample periods have fault data. Because.

Re: Car Q: accelerates for 2-3 seconds at a time then dies

Fuel pump relay if so equipped, but again with the fine/not....had one fail and it was just "not". Interested to see what this turns out to be.

Re: Car Q: accelerates for 2-3 seconds at a time then dies

Blaine- The artist formerly known as Plumber Crack "(OFMC)" /

Codes?

All you have is O2 “circuit fault” code, correct? Because it’s not even plugged in...

Since you have no O2 in the circuit, it won’t be able to generate any useful codes.

If you had a functioning O2 with an “B1S1 O2 “lean” P0171, i’d suspect a torn bellows between the mass air flow sensor and the throttle body, a vacuum leak, or low fuel pressure.

So will it sit and idle fine?

Once it’s up to speed to where only slight throttle is required to maintain your speed, is it ok then? (edited)

Re: Car Q: accelerates for 2-3 seconds at a time then dies

sits and idles fine, any throttle at all it responds normally for about 3 seconds, varying throttle position goes up/down totally normal until 3 seconds or so, then it cuts out completely until I release the gas completely, then I get another 3 seconds of normal operation.

it will die after 3 seconds of light throttle, or 3 seconds pedal to the metal, at speed or stopped.

It hasn't had O2 sensors in over 3000 miles, even passed e-check without em, never an issue til recently, only thing that seems related is the full dead battery, but maybe that's coincidence.

both sensors throw circuit faults. If I plug them in it'll barely run at all. The front one doesn't seem to do anything, always circuit fault, while the post-cat one makes it run like trash, no power, cant go anywhere, barely idles. (I refer to the pre-cat O2 sensor as "front")

The muffler shop totally stripped the seized front O2 sensor, it's extremely stuck and un-grabbable. I can get the back one out pretty easy, but I know the front one's bad and I don't wanna just replace the 1 if I cant swap the other. probably needs a new exhaust to be able to fit a new front O2 sensor, there's no other option right now besides cutting out the old one and welding in a new bunghole.

Still I wouldn't mind it being the previously acceptable level of blind O2 sensor still working like a normal car. maybe running it like that crashed the ECU?

Re: Car Q: accelerates for 2-3 seconds at a time then dies

Overpriced Parts /

> Blaine- The artist formerly known as Plumber Crack "(OFMC)" Wrote:

> -------------------------------------------------------

> Codes?

>

> All you have is O2 “circuit fault” code, correct? Because it’s not even

> plugged in...

>

> Since you have no O2 in the circuit, it won’t be able to generate any

> useful codes.

>

> If you had a functioning O2 with an “B1S1 O2 “lean” P0171, i’d suspect a

> torn bellows between the mass air flow sensor and the throttle body, a

> vacuum leak, or low fuel pressure.

>

> So will it sit and idle fine?

>

> Once it’s up to speed to where only slight throttle is required to

> maintain your speed, is it ok then?

Blaine has pretty much the correct diagnosis

He be the man when it comes to automotive repair🚘🚖🚐🚚🚛🏎🚙🛺

Re: Car Q: accelerates for 2-3 seconds at a time then dies

I was going to say most cars I have had o2 censor codes will still run normal. I used to be a vw guy with the old cis systems but sounds more like a mass airflow thing? The 2.slows are still pretty basic as computer stuff goes. Go on vwvortex and search around. I'm sure you will find an answer there.

Re: Car Q: accelerates for 2-3 seconds at a time then dies

Overpriced Parts /

Mopar with 800-850 cmf 4v Thermoquad With mechanical air door secondaries Rule!

Blows away any of this oxygen sensor, all this stuff far as performance but not MPG but It’s work worth looking into as far as induction because it was way ahead of its time

Re: Car Q: accelerates for 2-3 seconds at a time then dies

Is the throttle light coming on?

Re: Car Q: accelerates for 2-3 seconds at a time then dies

Try unplugging the airflow sensor and see if it still cuts out on you

Re: Car Q: accelerates for 2-3 seconds at a time then dies

Blaine- The artist formerly known as Plumber Crack "(OFMC)" /

Does it do the 3 second cutout sitting still if you just rev the throttle and try to maintain like 2500-3000 rpm in park or neutral?

Does the fuel rail have a schrader valve that you could check fuel pressure?

Re: Car Q: accelerates for 2-3 seconds at a time then dies

Fuel rail pressure sensor maybe. Just put one on a Freestar. The immediate shutoff, though, is strange.

Also fuel pressure should throw a code.

Re: Car Q: accelerates for 2-3 seconds at a time then dies

I'm assuming you've checked for vacuum leaks? I've had fuel injected cars behave very weirdly from cracked vacuum lines.

Re: Car Q: accelerates for 2-3 seconds at a time then dies

Yes, especially a vacuum line going to a fuel rail pressure regulator.

Re: Car Q: accelerates for 2-3 seconds at a time then dies

Blaine- The artist formerly known as Plumber Crack "(OFMC)" /

Shut up donnie. Nobody used fuel rail pressure sensors in 1998.

We’re all assuming fuel here. Have you ruled out ignition? Viewing a simple inline spark tester during a cutout event would be a quick and easy test of spark.

One that you can see the spark jumping about an 1/8” gap. Not the junk ones that have a glowing bulb. Just stick it inline in the center of the distributor.

184D2CAF-54C2-4C2F-A630-22411F2722D7.jpeg

Re: Car Q: accelerates for 2-3 seconds at a time then dies

punkrock randy /

One time my MK3 2.slo rubbed the o2 sensor wiring on something long enough to cause a short which would blow the fuse, shared with the fuel pump. Got stranded in Belevedere, IL on Xmas. Terrible. I’ll keep scratching my head and ask my buddy at the local v dub shop. Not sure on this one yet.

Re: Car Q: accelerates for 2-3 seconds at a time then dies

punkrock randy /

My buddy’s TPS gave him shit sounding similar on his yota pickup awhile back. Revved up readily until about 3k and would just drop back off.

Re: Car Q: accelerates for 2-3 seconds at a time then dies

.

20200813_074314.png

Re: Car Q: accelerates for 2-3 seconds at a time then dies

I miss Car Talk.

We could use that style though.

- Okay okay, you say... the cah will drive if you only push the gas for three seconds? Hahahaha Hahahaha Hahahaha (snort) Hahahaha Hahahaha haha.

So... why not just drive it like that? Bahaha (snort) hahah Hahahaha Hahahaha

You could, you could, you could build an electric motah with a cam that rotates...

“No No no, I see where you’re going with this. This guy wants you to hook ya gas pedal up to something that presses the throttle open once every three seconds.”

Bahaha haha Hahahaha (snort).

Try replacing your gas cap. Try that and call us back. Hahahaha Hahahaha whaahahah.

Snort.

Re: Car Q: accelerates for 2-3 seconds at a time then dies

> Blaine- The artist formerly known as Plumber Crack "(OFMC)" Wrote:

> -------------------------------------------------------

> Shut up donnie. Nobody used fuel rail pressure sensors in 1998.

Shut up,Blaine, and learn something,Boy...............LOL!

https://www.autocodes.com/p0191_1998_ford_f150.html

Re: Car Q: accelerates for 2-3 seconds at a time then dies

You probably have a split in the air boot between the maf sensor and the throttle body. When the engine moves on the old motor mounts (if one isn't broken) unmeasured air gets pulled through the split causing the lean drop off.

Have also found that engine movement can open electrical connections causing the same problem.

Re: Car Q: accelerates for 2-3 seconds at a time then dies

Get a CAN sniffer, or make one with an arduino. Plug it in and drive around. See what sensors are saying what as the car dies.

Re: Car Q: accelerates for 2-3 seconds at a time then dies

VWs had the lesser complicated fuel pressure regulator. Still, could be your problem, or the vacuum going to it. Unplug the MAF sensor and see how the car behaves.

Re: Car Q: accelerates for 2-3 seconds at a time then dies

Blaine- The artist formerly known as Plumber Crack "(OFMC)" /

> Don Ohio Wrote:

> -------------------------------------------------------

> > Blaine- The artist formerly known as Plumber Crack "(OFMC)" Wrote:

>

> > -------------------------------------------------------

>

> > Shut up donnie. Nobody used fuel rail pressure sensors in 1998.

>

> Shut up,Blaine, and learn something,Boy...............LOL!

>

> https://www.autocodes.com/p0191_1998_ford_f150.html

Yep, P0191 is a fuel rail pressure sensor circuit code.

No 1998 Ford that you will ever own will have a fuel rail pressure sensor.

I’m livin’ the dream donnie.

Re: Car Q: accelerates for 2-3 seconds at a time then dies

> Blaine- The artist formerly known as Plumber Crack "(OFMC)" Wrote:

> -------------------------------------------------------

> > Don Ohio Wrote:

>

> > -------------------------------------------------------

>

> > > Blaine- The artist formerly known as Plumber Crack "(OFMC)" Wrote:

>

> >

>

> > > -------------------------------------------------------

>

> >

>

> > > Shut up donnie. Nobody used fuel rail pressure sensors in 1998.

>

> >

>

> > Shut up,Blaine, and learn something,Boy...............LOL!

>

> >

>

> > https://www.autocodes.com/p0191_1998_ford_f150.html

>

> Yep, P0191 is a fuel rail pressure sensor circuit code.

>

> No 1998 Ford that you will ever own will have a fuel rail pressure

> e sensor.

>

> I’m livin’ the dream donnie.

Huh? The Lincoln and mustang's 4.6 use a fuel rail pressure sensor from like 97 I think. Just worked on one with a leaky sensor.

Re: Car Q: accelerates for 2-3 seconds at a time then dies

^ Was thinking that too, but not 100% sure...any idea where it is located? May be my issue....

Re: Car Q: accelerates for 2-3 seconds at a time then dies

Blaine- The artist formerly known as Plumber Crack "(OFMC)" /

Nope.

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