99 RS 420a hesitation and bucking

[Hall7910]

Ok, first off, new here and my first eclipse. 1999 Eclupse RS non turbo. When I bought this car, 3 months ago, I drove it home and around for the first week with no issues. After that 1st week...after it warms up, it will start hesitating and bucking on me. Doesn't matter the speed or where tge rpms are. Getting good spark. New plugs, wires, control module, fuel filter, fuel pump, ecm, vacuum lines are good. Fuel pressure at idle sits at 49-50. Under a load about 47. I've racked my brain and read thread after thread, but when the issue is described by others, their cars are turbo amd it seems to have to do with that. I've done ohm readings on sensors and the control module, everything is where it needs to be. I removed the throttle body and completely cleaned it up. My next option is the intake manifold and clean it up as best I can. I dunno. I'm stuck and could use some advise or help if anyone else has had this issue.

Thanks in advance.

 

[Kenny07]

Welcome!

Did you gap the plugs correctly? Maybe injectors? Or timing is off? Vacuum leak around the manifold? Try running a can of Seafoam through it, put a can in the gas tank, and use a half of a can in the vacuum lines, that will clean a lot of build up out. Get ready for a smoke show though.
Does it die on you or just misfire while at idle/under load?

 

[Hall7910]

Sorry, new injectors as well. Replaced with new oem injectors. I've run seafoam thru it with the first tank of gas. I put another one in today. I'm only on the 3rd tank all together. I wound up replacing all the vacuum lines because some of them were brittle and breaking. I also rigged up an at home fuel induction service. Vacuum hose, bleeder valve, and can of injector cleaner and wedged the gas pedal down to hold around 2500 rpms tons and slowly fed tge cleaner thru. Smoke everywhere for a little while. Drove it afterwards about 15-20 Mikes to clear the system, still had the issue. Timing is fine and checked gap before I I stalled new plugs. Used NGK irridium plugs.

 

[Hall7910]

Please excuse my typing here...my phone is being stupid...typically it idles just fine. It's died once or twice at idle. Also I have no check engine light and no codes stored. It rarely dies on me. Normally I'm at a high enough speed, it kicks back in after 3-5 seconds of nothing. It normally does this under a load.

 

[Kenny07]

Sorry, new injectors as well. Replaced with new oem injectors. I've run seafoam thru it with the first tank of gas. I put another one in today. I'm only on the 3rd tank all together. I wound up replacing all the vacuum lines because some of them were brittle and breaking. I also rigged up an at home fuel induction service. Vacuum hose, bleeder valve, and can of injector cleaner and wedged the gas pedal down to hold around 2500 rpms tons and slowly fed tge cleaner thru. Smoke everywhere for a little while. Drove it afterwards about 15-20 Mikes to clear the system, still had the issue. Timing is fine and checked gap before I I stalled new plugs. Used NGK irridium plugs.

Well, were dwindling down what it could be. Maybe a gasket around the Intake manifold or injector seal leak, if you don't have stethoscope, then while the car is running stick a vacuum line down by the intake manifold, Injector seals or pretty much wherever there's vacuum and listen to see if you can hear air blowing over the end. Not sure if i'm explaining that so you can understand, but you're basically listening for vacuum leaks.
Maybe cam/crank sensors? But i'm really not to familiar with 420's, sorry.

 

[Hall7910]

Well, were dwindling down what it could be. Maybe a gasket around the Intake manifold or injector seal leak, if you don't have stethoscope, then while the car is running stick a vacuum line down by the intake manifold, Injector seals or pretty much wherever there's vacuum and listen to see if you can hear air blowing over the end. Not sure if i'm explaining that so you can understand, but you're basically listening for vacuum leaks.
Maybe cam/crank sensors? But i'm really not to familiar with 420's, sorry.

Replaced the injector seals with the new injectors. I've checked for other vacuum leaks as well and come up with nothing. I'm at a total loss. Talked to a few mechanics and they are stumped as well. Even had one scan the car with his computer, which was rather nice...I was a bit jealous...and even he came up with no codes or anything stored. I will say yhe car ran great for about 150 miles after I put the new fuel pump in. After that, started doing it again. The latest mechanic said pull the TB and clean it...so I did. The intake manifold looks like shit shot on the inside...so I'm wondering if it just can't breathe like it needs to. It took me over an hour to clean the TB up. A lot of Crap was gummed up on the butterfly plate.

 

[Kenny07]

Well, were dwindling down what it could be. Maybe a gasket around the Intake manifold or injector seal leak, if you don't have stethoscope, then while the car is running stick a vacuum line down by the intake manifold, Injector seals or pretty much wherever there's vacuum and listen to see if you can hear air blowing over the end. Not sure if i'm explaining that so you can understand, but you're basically listening for vacuum leaks.

Replaced the injector seals with the new injectors. I've checked for other vacuum leaks as well and come up with nothing. I'm at a total loss. Talked to a few mechanics and they are stumped as well. Even had one scan the car with his computer, which was rather nice...I was a bit jealous...and even he came up with no codes or anything stored. I will say yhe car ran great for about 150 miles after I put the new fuel pump in. After that, started doing it again. The latest mechanic said pull the TB and clean it...so I did. The intake manifold looks like sh** shot on the inside...so I'm wondering if it just can't breathe like it needs to. It took me over an hour to clean the TB up. A lot of Crap was gummed up on the butterfly plate.

Well I'm stumped as well, maybe some of the wisemen will chime in. If it's sensor related you may not get a code, could just be poorly fuctioning so just because you don't get anything from a scanner doesn't mean you don't have a "bad" sensor somewhere. My cam sensor was bad and caused a misfire but never gave a code, but like I said, I'm not familiar with the 420s.

 

[PlanZero]

Check the tps, or swap it with a known good one or even junkyard part. My old gs would shudder and buck usually either taking off or slowing down to/from a stop. I think the tps tested OK according to the Haynes manual (n/t tps isn't adjustable), but I swapped it with a junkyard pocket part and all my issues went away. It seems to be more problematic on automatics. Also, these cars run better on copper plugs, I believe non turbos used champion, but ngks will be fine.

 

[Hall7910]

Check the tps, or swap it with a known good one or even junkyard part. My old gs would shudder and buck usually either taking off or slowing down to/from a stop. I think the tps tested OK according to the Haynes manual (n/t tps isn't adjustable), but I swapped it with a junkyard pocket part and all my issues went away. It seems to be more problematic on automatics. Also, these cars run better on copper plugs, I believe non turbos used champion, but ngks will be fine.

Thanks...I'll try it. I did pull the fuel rail again...was gonna pull the intake and try to clean in up as best as possible...but when I pulled the rail, the gas coming out was orange. I'm wondering if the fuel tank is rusted and causing these issues...any thoughts?

 

[Jsrunnlus]

I do have a 1999 sitting here right now that has a fuel filler neck vent line that rusted through. Closer examination shows rust on the filler neck as well.

Obviously rust is a contaminant with particles that affect fuel flow and in the case of mine with open system can result in condensation or water introduction which further decreases fuel stability.

 

[Carmike474]

Hey i am new here, but i have replaced mostly all of what you said and found out my problem is been the fuel pressure regulator the entire time and contaminated fuel lines after replacing everything else!