01 Lesabre is gasping for air/fuel

[lesabrefan]

Noticed this twice, when going around 40 and up a little hill (so the engine is not really struggling), it feels like the engine has 3-4 quick gasps for fuel and then everything goes away. It's probably hard to diagnose over the web, but maybe somebody had the same problem?

As a side note...

I tried to reproduce that in park (I thought it was RPM related), when i revved up to 4000 RPM, the engine began to shake and I could not get past 4000. I thought the issues where connected, but I've read on the net, that cars have a soft limit in P/N and will no allow you to get past 4000. It seems not many people realize their cars have those limits, so just thought it was curious, I doubt many people rev their engines to 4000 in P/N

[HotZ28]

I think your problem is secondary ignition misfire i.e. coils, wires, plugs. You should check the fuel pressure anyway to be sure it is up to par. There is a rev limiter set in the PCM while in P/N, but I can not imagine anyone revving an unloaded engine far enough to experience that. Misfire can be detected better under load, such as holding the brake & bringing engine rpm's up to 1500 to see if you have shudder.

[maxwedge]

Yeh, all the Toyo owners are afraid to put the car in neutral during the alleged runaway, it may blow the engine! LOL

[lesabrefan]

HotZ28, the wires and plugs have recently been replaced. How can I check that the coil is functioning correctly, in a similar thread, the following was suggested: "Look around the coil terminals, where the metal stud comes out of the coil housing. If there is a black residue, that coil is likely bad." How do I check the coil terminal, where's is it located and what does it look like?
Thanks

[lesabrefan]

9 months later, the same thing is still happening. I replaced coil packs with the same type from another car, did not fix the problem. While the engine is running, I unplug each spark plug wire and notice a change in the engine's performance, so I would assume each spark plug is working. The fuel pump and fuel filter have been replaced.
Here's what still happens, when the speed is about 30-40 and the car starts going up a little slope, the engine might sputter, if I release the gas for a second and press on the gas pedal again, everything is fine. If i'm on a highway and slowly bring the car up to 60-65-70, everything works perfectly fine. If I attempt to give it a little more gas and speed up a little faster the engine might sputter, once again, foot of gas and foot back on gas solves the problem. What else could it be?

[maxwedge]

Hey, still digging out no, so why drive it? My son lives in Prospect Park area. Good luck!! That still can be ign. because your test is done when the engine is not under load. A full scan can look at misfire counts so that would help see if it is ign related.

[lesabrefan]

Maxwedge, I forgot the most important thing. If I don't take the foot of the gas and let the engine sputter for a couple of seconds, Check Engine light begins to flash, so that means there's a misfire. Would that piece of info help in any way?

[danielsatur]

You Need Air, Fuel, and Exhaust for horse power.
AIR:
1) New Air filter
2) Clean Massive Air Flow(MAF) sensor with CRC MAF sensor cleaner.
3) Clean Throttle body, and IACT.

FUEL:
4) New fuel filter
6) Fuel pressure test

EXHAUST:
7) Have your catalytic converters checked at a local muffler shop.

[lesabrefan]

danielsatur, thanks

You Need Air, Fuel, and Exhaust for horse power.
AIR:
1) New Air filter - filter is replaced
2) Clean Massive Air Flow(MAF) sensor with CRC MAF sensor cleaner. - MAF was replaced recently
3) Clean Throttle body, and IACT. - throttle body has been cleaned, don't know what IACT is...

FUEL:
4) New fuel filter - filter is replaced.
6) Fuel pressure test - the test has not been done, but is it possible that the fuel line is the problem, if I can easily get up to 70 MPH with a gradual gas application?

EXHAUST:
7) Have your catalytic converters checked at a local muffler shop. - same question here, could CC cause a misfire?

[maxwedge]

A full scan will look at misfire counts and most likely pin down the suspect cylinder/s, the flashing cel means you have an ign type misfire. Any other work done is guess work and /or normal maintenance.

[danielsatur]

Doing regular routine maintenace can actually weed out, and
prevent problems.

Random misfires canbe caused by a bad air filter, fuel filter. or a bad catalytic converter.
See http://www.automotiveforums.com/vbul...d.php?t=972629

[Blue Bowtie]

Not that the Wedge Driver needs any backup, but I'll second the suggestion to scan the PCM for stored and pending DTCs. I'm guessing you will find misfire codes pointing to a specific cylinder(s) and indicating either weak spark or poor fuel delivery in those holes.

One thing to remember is that at low RPM cruise the injectors are delivering low volumes of fuel, and a streaming injector (poor spray pattern) can cause a misfire just like a weak plug or coil at low throttle openings. At higher RPM a solid stream of fuel (as opposed to a finely atomized cone) is vaporized better by the higher air flow and higher intake temperature, and becomes less of a problem. Intake temperatures can become very low at low throttle openings, hindering fuel atomization. Any of the other "old guys: here who have ever experienced carburetor icing would recall that.

Similarly, fuel pressure at the low end of the allowable range, and injectors with partial restriction or higher propagation delay can cause poor fuel delivery under these conditions, and operate "normally" under higher load and RPM conditions.

In short, once you've determined which cylinder(s) is involved and have exhausted the ignition system possibilities, don't overlook the fuel delivery.