Engine sputters sometimes when accelerating but acts normal when restart

[Size9zombie]

main relay replaced but still same sputter. My possibilities left IMO are fuel pump, fuel filter or foreign object in gas tank.
Symptoms are
1. Entire engine sputters but no backfiring and seemingly no misfiring. It is like someone just turned off fuel so it can only idle.
2. It still idles properly even when this is happening. I can just let off gas and it idles fine but will still sputter if i hit gas.
3. Symptoms range in time it does this. From a second or 2 to 10 to 15 seconds on occasion.
4. All other electrical components work fine while this is happening.
5. This has always happened driving at lower rpms between 1200 to 2700. Never yet has it sputtered above 2700.
6. If I cut off engine and restart all symptoms go away.
7. This happens no matter the engine temp.
8. Engine never sputters while revving up engine. It always happens while driving at low speeds and rpm's.
9. Engine never sputters above 35 mph. I also rarely go anywhere that speed limit is above 45. So am not sure how accurate this symptom is.
10. Symptoms have became more frequent over a month and about 140 miles of driving.


things ruled out and why?
1. Cat- Sputtering happens when engine is cold or warm and restarting car it immediately goes away.
2. o2 sensor- no cel. O2 sensor is new and this started with old O2 sensor replaced a few weeks ago.
3. Main relay- Was replaced today.

other possibilities?
1.something else in dizzy besides ICM which was replaced a couple days ago(I had a spare i put in).

Any other possibilities please share.

That's different than what you initially said.

[Size9zombie]

https://www.delphiautoparts.com/usa/...w-troubleshoot

[zedjr10]

Sorry about that, wrong pics. Here is a diagram .

i got a service manual. Could it be the evap system. That thing cuts on at like 167f and above 3500 rpms. Wouldn't i see that though in my fuel pressure gauge. What else activates at about 170 and above 3k or so rpms and then suppose to change when it gets below 2k or something. The things I see that do this are part of the evaporative emission controls which is evap and egr. Am also going to test some more and confirm this only happens when coolant temps are above 170 and with rpm's raised and dropped again.

[zedjr10]

That's different than what you initially said. That sounds more like a restricted exhaust.

the only thing that has changed is that it seems to only do this when coolant temp is above 170 and after it has been above 3k rpms and dropped back down. Am not totally sure of this as i think one time leaving parking lot it did this before engine getting up in any rpm's. But not sure about this. More testing is needed now that I know what to look for.

[zedjr10]

Replaced black box with egr control solenoid and whatever else is in there. Still same issue. Would the cat cause this given the temp and rpm conditions?

[zedjr10]

That's different than what you initially said. That sounds more like a restricted exhaust.

ok update since more testing. I think number 5 is key.
1. This happens at any engine temp. Got it to sputter with cold engine twice.
2.The frequency has gotten alot more in last week or 2. Every couple miles driving thru residential streets.
3. The sputter isn't a backfire it is just a total loss of power and can't accelerate.
4. If I let off gas it idles fine.
5. If I push in clutch I can rev up engine just fine but if I put it back in gear it sputters again.
6. This has always happened driving at lower rpms between 1200 to 3200. Never yet has it sputtered above 3200.
7. Symptoms range in time it does this. From a second or 2 to 10 to 15 seconds on occasion. Eventually it returns to normal operation.
8. No cel at any time.
9. Restarting engine all symptoms go away and returns to normal. Even though it can be only another 1/2 mile before it starts again at times.
10. The sputtering seems to be totally random but has gotten a lot more frequent in last 2 months.

Possibilities
1. Dizzy - does the dizzy act different when under load and applying gas.
2. Ignition Coil - unlikely as only a few cylinders sputter at it always idles and revs up fine.
3. Cat - I still don't think this is likely as why does it work fine after I restart. And why not at higher rpms. Would partially blocked cat cause this at any engine temp i wonder.
4. EGR lift valve Sensor - a sensor is causing this thing to act erratic but why does this not happen when revving up while clutch pressed in.
5. Something in fuel system - Fuel pressure seems to be operating fine even when sputtering. When it is sputtering i can hit gas and i see pressure goes up fine like I am assuming it should. Never goes below 30 and never above 40. Fuel pressure reflects how far i am pushing on gas pedal.
6. Fuel injectors- 2 to 3 cylinders seem to be acting up so unlikely imo.
7. Some other relay somewhere other than main relay- unlikely i think cause it revs up fine while sputtering is going on. I push in clutch and revs up fine.
8. A bad sensor somewhere?- but again why does it rev up fine as soon as I push clutch in and then return to sputtering as soon as i release it.
9. Evap Canister?

Things it can't be
o2 sensor- was replaced with oem one and still acting same way.
eec box with egr solenoid and evap stuff - Was replaced with spare
fuel filter - replaced
ICM - swapped out
Fuel Relay - replaced.

Anyone got any other possiblities?

[Raf99]

How long do you leave the car off to resolve the issue?
Have you ever looked at your fuel return / FPR (fuel pressure regulator)?
Can we see a picture of your spark plugs?

Vacuum should be mentioned here too. A gasket past the MAP sensor under certain loads could be leaking (occurring when hot) resulting in this issue.
https://mechanicbase.com/engine/vacu...mptoms-causes/

[zedjr10]

How long do you leave the car off to resolve the issue?
Have you ever looked at your fuel return / FPR (fuel pressure regulator)?
Can we see a picture of your spark plugs?

Vacuum should be mentioned here too. A gasket past the MAP sensor under certain loads could be leaking (occurring when hot) resulting in this issue.
https://mechanicbase.com/engine/vacu...mptoms-causes/

U mean when I restart, immediately I restart either by actually turning key or just by putting it back in gear and rolling starting it.
I have considered my fuel return and evap system but I don't know how I would test that when the sputtering happens randomly. Would the evap even cause this i wonder if it was malfunctioning. Why doesn't it happen at high rpms also.
FPR I have ruled out mostly cause my fuel pressure seems to be good. I got an electrical in dash fuel pressure gauge hooked up at end of fuel rail and fuel pressure seems to be operating normally.
Plugs are fine, i checked them. No oil or nothing leaking in there.

The whole magic black box I swapped out which has a new map sensor in it so it can't be anything in that black box which i think houses the evap solenoid, egr solenoid & and map sensor. It idles good and no signs of a vacuum leak anywhere.

Ok update again to my symptoms. It will sputter while in neutral. If i hold my pedal at a certain sport it will erretically sputter and drop rpms. I have to floor it then it will rev back up. My assumptions about it never doing this in neutral or while clutch is push in is wrong. SO given this info i think it is the TPS. I wonder why it goes away though when i restart car.

[zedjr10]

Ok one symptom i want to add as more testing i stumbled upon this. I think this will brake the case open. I honestly wish i could start this post all over and I appreciate any patience of anyone i have test and all the help and comments i have gotten. Thank you. I know it is frustrating with me sometimes.

1. If i start engine and keep throttle at almost any position eventually it will start to sputter and miss. This doesn't happen immediately at a throttle position. It usually take at least 15 seconds but can take up to one minute. The only way to stop it from sputtering is to let it idle again and sometimes I can just floor it and let it rev up high to 5k. While this sputtering is happen if i floor the pedal it will stop and rev up high normally.

TO me this sound less like tps and more like something in fuel. I am going ot swap out my FPR(got a used spare) and TPS(bought new one) later today but i don't think this is going to fix it.

Anyone got any thoughts on this or too frustrated with helping me. Again thanks for all the help and comments before.

[Raf99]

You're on the right track, hopefully lessons learned here. ( = me too frustrated). All sounds like TPS or fuel .... personally I'd like to see a pic of the plugs but I'm sick of asking.

[zedjr10]

You're on the right track, hopefully lessons learned here. ( = me too frustrated). All sounds like TPS or fuel .... personally I'd like to see a pic of the plugs but I'm sick of asking.

I got some pics of plugs and i will try to upload them. They really are fine. Last time couldn't figure out how to get them right file size(it's an ios). I don't even know what is going on anymore with this car. Yesterday I thought it was tps so today again i wanted to test again and confirm. TPS seems fine and isn't fluctuating. Am so frustrated. AM going to let it cool down and test again. Am beginning to think it is a sensor that affects fuel ratio decisions and nothing to do with fuel directly. TPS will stay exactly at .95 volts one minute at 3k rpms and next few seconds it drops down to 2k without throttle moving at all. Am just so frustrated and don't want to just change parts out. I guess I am going to get a good lesson on how to test sensors like the ect and others.

After testing some more i can bring on conditions once car is warmed up past 140 f. It never still does it at idle. I have to raise rpm's up to 2400 and it only takes a 10 or so seconds for sputtering to start.

My fuel pressure is at 32psi before it starts to sputter at 2500 rpms. Right after it starts to sputter and miss it drops down to much lower rpms and the fuel pressure raises up to 35. Honestly I am not sure what this tells me. Maybe the injectors aren't firing the fuel and it is building up in the line. That is my assumption but be nice if I could get a confirmation on that.

[Raf99]

You're also reaching the limit of your tools and experience I think. Almost time for a garage / expert to chime in, IE: honda technician or garage tech. I think next step here is to take a video of the issue and show us. This issue has gone from "no-one in the car would notice it" to "definitely breaking up (sputtering) when hot". And the vacuum hoses thing I mentioned all need to be checked. As soon as you start putting vacuum on the intake plenum it sounds like a hose is letting extra air in. This = bad air / fuel at that specific moment. Probably only happens when the hose is hot too. But ya.. .take a video and show us.

[zedjr10]

You're also reaching the limit of your tools and experience I think. Almost time for a garage / expert to chime in, IE: honda technician or garage tech. I think next step here is to take a video of the issue and show us. This issue has gone from "no-one in the car would notice it" to "definitely breaking up (sputtering) when hot". And the vacuum hoses thing I mentioned all need to be checked. As soon as you start putting vacuum on the intake plenum it sounds like a hose is letting extra air in. This = bad air / fuel at that specific moment. Probably only happens when the hose is hot too. But ya.. .take a video and show us.

Hey i am getting there. My car never goes to a garage. I am the garage. This is well within my skill level. Please a garage. It isn't a hose getting hot or it would do this at idle, higher rpm's, lower rpm's or some other set of conditions.
It still isn't that noticeable when driving sometimes but that depends as it has definitely gotten worse over last couple months. I just stumbled upon what brings on the sputtering really. Which i should of tested better before. I need to yank out my ECM and start testing all the sensors probably instead thru that slitting lines and testing individually like i did the tps.

I still am wondering why my fuel pressure on rail rises 2.5 psi right after the sputtering starts. I am thinking the injectors aren't firing fuel and this is a build up but I really don't know. Maybe my absolute pressure lowers and that is why fuel pressure rises some but unlikely i think. Would be nice if someone could confirm or deny that.

I have eliminated most things but i still have a few left. The 2 most likely imo at this juncture would be dizzy and some unknown sensor.

1. ECM
2. Dizzy
3. EVAP purge canister
4. EVAP 2 way valve
5. EGR and lift valve sensor - Unlikely as letting off gas pedal and waiting the symptoms go away.
6. Unknown sensor like IAT sensor.

[zedjr10]

I really need to find out if this misfire is coming from injector side or dizzy side. I honestly don't know how to do this. Going to have to look this up. If it was coming from dizzy side then why don't my gas smell like eggs and why does fuel pressure shoot up almost 3 psi.

[Raf99]

Waiting for a video and pics of plugs