Hit gas bogs down

[TONYCASH]

When car is cold,no problem.Once it warms up and you hit gas,the it bogs down and wants to cut off.Took the CAT off thinking it was,maybe clogged.No difference.????

[25Horseplay]

Is this the same car you just changed the engine in? And is it doing the same thing as before?

[TONYCASH]

same car,different engine(known good engine).It is kind of doing what it did before.Starts right up(other one didn't).Runs great,responds good.Then when it is warm , you hit gas and it idles high,even after you let off gas it revs itself,sometimes.Still wants to cut off when hitting gas.UGHHHHHHHH!!!!!!!

[25Horseplay]

Did you change the coil? How about the ECU? Did you use the same air meter?

[Pu241]

Tony, hit us up with some details carbie/EFI anything else done to the engine, did engine run fine previously, did it sit for a long period of time.
We hear a lot about clogged Cats but in reality we rarely ind confirmation that the at is actually clogged. Now their is a difference between carbon clogged and cat support ceramic having melted.

[DriverOne]

I have the same problem. I'm not sure why, but the angle in which the car is sitting seems to play into that as well. I figured my carb had to be cleaned out, and I tried that, but there wasn't much improvement. I still have high rev on startup in any temperature, but after a few drops of the pedal it brings it down.

[TONYCASH]

it is a 1990 l pus,efi,auto w/air.Air has never been hooked up since we got it.It ran fine all the way home.Anyway,we put in the efi engine out of my 90 auto.Also,maf,disty and fuel pump,new fuel filter,plugs and wires.my engine ran and worked 100% until we put it in this car.it is better than the old one,but,still these problems.

[Burnrate]

did you swap in the known good intake (fuel pressure regulator) Swap ECU? Is there something electrical keeping the choke closed (or what ever an EFI does for choke) ? Bad Gas? A/C has some load relays. Is the A/C wiring completely unplugged?

[Burnrate]

Inspect the hard fuel lines under the car for accidental floor jack crimping. does it do it with the gas cap off?

[ericsmith32]

O2 censor?... it's out of the loop till it warms up. I can't remember it all but I think that's what fixed my 91.

[bobbyspider]

your stock intake could have a tear in it and when you hit the gas and the motor rocks it opens the tear and does not allow air to pass through the mass air flow sensor because its in front of the tube. this happened to me when i had an old fx 16 gts it took along time to figure it out because the tear was on the bottom of the intake tube and when the motor doesnt have a load on it the crack will be completely shut. giv it a look its just a thought.

[TONYCASH]

Ok,I am home now.I will start from the beginning...
Bought the car(90 L Plus,auto,air,efi)last summer.Drove it home 6 hrs.Ran good.No problems(little shaking in front).Mom drove it all this summer until it started dying at red lights and soetimes not starting when she came out of store.Sometimes you would back out of driveway,put it in gear and it would die and not restart for a long time.She took it to some "mechanic" and it came back WAY WORSE!
Now,when we got it back it would barely start.GenevaDirt and I messed with it for a couple hours...changed a lot of things over from my car and his that we thought might be the problem.e.g...disty,maf,tps,coil and other things.Nothing changed.I decided to just swap out my 102k mile engine from my 90 LX,that was 100%great running order.We did that.We swapped engine and everything on the engine as a whole unit.We swapped in my MAF,radiator,ignition coil,fuel pump,new plugs,wires and a few other things.
Car starts right up every time.Seems after it warms up it wants to up its idle on its own.Not always,but,mostly.
Once it warms up and you give it gas it wants to bog down/try to shut off.If you baby the throttle it goes much better.Granted this engine still starts up on the first try..other one didn't.but,once warm...well,you know.
All we can think of it HAS to be something off of the engine.Something we DIDN'T change that stayed with the car.
I have included a lot of pics of enine.Maybe someone will see something we didn't.Also,there is oil residue in the top tube running to MAF.














this is what happens when u r 2 close to heater with your butt.!!!

[ericsmith32]

Looks like your o2 sensor is factory. I'm starting to remember some of the problems I had. Several times mine would die when hot and wouldn't restart till cold. Did alot of cutting out from what I could remember when it was hot. Change your o2 it's cheap. That's the only thing we change and it stopped.. luck don't know.(me and friend was having a hell of a time with it)

[bills]

Check the Timing for TDC if the belt was changed out recently or before the swap. After the engine warms the timing will retard and if the belt is off a tooth this will cause a similar symptom of loss of power, stalling or response. I also had a small nut that fell down in the timing cover area one time that caused the belt to jump a notch.

[GenevaDirt]

the engine that is now in this car came out of a car that ran perfectly fine....no issues what so ever. O2 sensor worked in the previous car....
Only a couple things were not from the other car ,the wiring harness and the ecu....

I am thinking in my uneducated guess....ECU