Jump to content
LegacyGT.com

99GT Stumble/bog/misfire mystery


Recommended Posts

Hello all,

 

Car: 99 GT wagon 5mt. 182,000 miles

 

Issue:

 

Car stumbles and bogs under load and when blipping the throttle at idle.

 

When the engine is cold and the idle is still high, I can blip the throttle all I want and there is no sign of stumbling or bogging.

 

Problems begin when the car warms up.

 

If I very gently give throttle the engine revs smooth.

 

If I blip throttle the engine stutters and bogs.

 

Driving is the same, if I am very gentle on the throttle is revs fine, but as soon as I put my foot down it bogs and stumbles like crazy until it gets to about 3k rpm- feels like its misfiring.

 

Things I have done:

 

Replaced Upstream 02

Tested knock sensor with multimeter, inspected for damage / cracks

Replaced Ignition coil (primary coil tested at 1ohm both leads)

Replaced all vacuum lines & checked for vacuum leaks with propane and water

Checked & cleaned Crank position sensor

Checked & cleaned Cam position sensor

Cleaned IACV

Cleaned MAF (with crc maf cleaner)

Checked ignition timing with timing light

Changed oil

Checked plugs (they looked alright)

 

Best of all, NO CHECK ENGINE LIGHT

 

New NGK wires will be delivered tomorrow

 

I am at a loss otherwise! Please Help!!

Link to comment
Share on other sites

Well you did everything I would have started with haha. Maybe a fuel thing? Pull the inlet hose and check for water, pull the filter off and try to blow through it. Check the air filter if you haven't already. Maybe replace the fuel pump sock if you find anything odd about the fuel
Link to comment
Share on other sites

Check your cam belt hasn't jumped teeth. That is not completely unlike how mine ran when one cam jumped 2 or 3 teeth. The time warp in the computer when the cam and crank sensor say 'we are at 0 degrees' at different times get spark and injector all confused. Skips some and doubles up on some. But no check engine light.
Link to comment
Share on other sites

The local parts store is open till 9 around here so I said why not and ran down to pick up a fuel filter.

 

Let me say, the fuel pump relay in a 99 legacy is nearly impossible to reach unless you have arms the size of twigs, as its way up in the dash.. I had to use a long needle nose to grab the tab and pull it out.

 

Anyway I got the filter in and it was a night and day difference. Totally solved my issue!! Smooth revving from idle and up with no stumble! Amazing what a clogged fuel filter can do to your cars performance.

 

Thanks again brighton96!!

Link to comment
Share on other sites

Swweeett! Glad it fixed it. I would also do the fuel pump sock in that case. It's only like $7 and takes about 35 mins to swap, worst part is your interior will smell like gas for a couple days. But if the fuel filter was that bad, I can't imagine the sock haha.
Link to comment
Share on other sites

Wait, I lied. I forgot how many ounces a normal water bottle is. It was 16.9oz in about 15 seconds. And yes you mind as well get it over with while you are there, make sure to get a new rubber tank seal when you do this too, chances are the old one is dried out. 180k is considerable for a pump so even if it's still good, I'd replace it and keep the old one as a back up.
Link to comment
Share on other sites

I calculated 25.425 gallons per hour. I wasn't able to find the specs of the Bosch one, when I searched specs I just got useless information like package size and pump weight. But the Denso OEM replacement says max of 50gph at a max pressure of 85-90psi.
Link to comment
Share on other sites

Same as me, just shipping info and related crap.

 

I'm chasing a flat spot at WOT near redline. I expect I've passed the end of what the factory ECU can handle. I was just checking if fuel flow might be the problem. I need to get a spare bung welded in my new exhaust so I can put the wideband back in...

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.



×
×
  • Create New...

Important Information

Terms of Use