Hello Everyone,
New member here. I've been using this site for a resource for the last 3-4 years when i picked up my 99 2.5. You all have been a great help, so i'm hoping you can help out here too! I'm stuck on this one and i don't see anyone with any similar issues, so looking for some pointers.
Car info:
- 1999
- 2.5 L
- Manual 5spd
- 135K miles
- lifted with 33's
Fist off, what i've 'touched' over last year:
* New Sparks (champions .35 spaced) / wires / cap / roter
* New battery terminal cables (custombatterycables.com)
* New Exhaust Manifold (old one had cracked, replaced by shop, cracked again within 4mo, under warrenty shop replaced)
* New Fuel Injectors (STP double platinum) ** after install reset sensors**
* New O2 sensors (NTK - upstream and downstream) ** after install i reset sensors **
* New Idle Air Controller (1st item ever replaced, done by shop, may need to revisit)
Now the issue:
Cranks up, no problem. Sitting idle, no problem. Start driving, no problem.
i get to about 40 mph, about 4th gear, between 2.5 RPMs and 3K, and it starts. Best way i can describe it is a 'bucking' or 'jerking' sensation. Happens for a split second, then levels out. But it can happen again in quick concession. My reaction has been to release the gas, dropping the accelleration, and coast until 3rd gear then try again... same results. even if i push through and try to get to 5th gear, it still happens...
Visually during the issue, no codes. Dashboard - Oil/Gas/Temp gauges remain unchanged. Mileage stays lit. Noticed Oil pressure seems on the high side, but within acceptable range. RPM and SPEEDOMETER are dying then coming back, for every jerk the needles fall and return.
So to see this issue under various scenarios i tried not driving on the highway, and i did confirm the issue doesn't happen at lower speeds.. basically if i keep her under 4th gear (-40 mph) then never see the issue. Now this is FL, and everything is flat.. so i thought i would try the same test out but on a tall bridge, trying to rule out the speed factor, which would isolate to stress?. And i was successfully able to see the issue while 'climbing' uphill. In this case the issue happened all the way from bottom to the top of the bridge even while only going 20 mph and staying around 2nd to 3rd gear. once at the top, i kept the gear engaged, took foot off gas, and let her coast to the bottom. Here i noticed no jerking or bucking, but the needles (RPM and SPD) were dying and coming back over and over.
Leads:
- Not electrical - if it was, wouldn't i have lost power to the radio and dashboard? (all needles would have fallen, mileage would have gone dark?)
- Misfire? - right before this started, i had a misfire code in cyl 3, but that was fixed after Fuel injectors replaced, issue could be stil there? but yet no codes, and no smell of gas.
- Oxygen? - new upstream and downstream O2 sensors, but maybe a vacuum leak? under stress would make it worse causing a choke, making the engine die?
- Fuel? - possible fuel pump failure? or bad Fuel pressure regulator? Needed at high speeds?
** also i have one of those OBD services (AUTOMATIC) where you can plug in and do various things. While this issue is happening, it is reporting that the car is "turning off" and "turning on" over and over. So when i drive say to work and never see/feel the issue, the dongle shows that i've taken 6 trips... but this may be a completely separate issue, so not considering it, but its information that out there.. **
Ok... i'm hoping you all can help me out on this one.. i'm an amateur with the tools, but willing to work through it if its within my skill set.. otherwise i'll take it to mech.
Thanks!
New member here. I've been using this site for a resource for the last 3-4 years when i picked up my 99 2.5. You all have been a great help, so i'm hoping you can help out here too! I'm stuck on this one and i don't see anyone with any similar issues, so looking for some pointers.
Car info:
- 1999
- 2.5 L
- Manual 5spd
- 135K miles
- lifted with 33's
Fist off, what i've 'touched' over last year:
* New Sparks (champions .35 spaced) / wires / cap / roter
* New battery terminal cables (custombatterycables.com)
* New Exhaust Manifold (old one had cracked, replaced by shop, cracked again within 4mo, under warrenty shop replaced)
* New Fuel Injectors (STP double platinum) ** after install reset sensors**
* New O2 sensors (NTK - upstream and downstream) ** after install i reset sensors **
* New Idle Air Controller (1st item ever replaced, done by shop, may need to revisit)
Now the issue:
Cranks up, no problem. Sitting idle, no problem. Start driving, no problem.
i get to about 40 mph, about 4th gear, between 2.5 RPMs and 3K, and it starts. Best way i can describe it is a 'bucking' or 'jerking' sensation. Happens for a split second, then levels out. But it can happen again in quick concession. My reaction has been to release the gas, dropping the accelleration, and coast until 3rd gear then try again... same results. even if i push through and try to get to 5th gear, it still happens...
Visually during the issue, no codes. Dashboard - Oil/Gas/Temp gauges remain unchanged. Mileage stays lit. Noticed Oil pressure seems on the high side, but within acceptable range. RPM and SPEEDOMETER are dying then coming back, for every jerk the needles fall and return.
So to see this issue under various scenarios i tried not driving on the highway, and i did confirm the issue doesn't happen at lower speeds.. basically if i keep her under 4th gear (-40 mph) then never see the issue. Now this is FL, and everything is flat.. so i thought i would try the same test out but on a tall bridge, trying to rule out the speed factor, which would isolate to stress?. And i was successfully able to see the issue while 'climbing' uphill. In this case the issue happened all the way from bottom to the top of the bridge even while only going 20 mph and staying around 2nd to 3rd gear. once at the top, i kept the gear engaged, took foot off gas, and let her coast to the bottom. Here i noticed no jerking or bucking, but the needles (RPM and SPD) were dying and coming back over and over.
Leads:
- Not electrical - if it was, wouldn't i have lost power to the radio and dashboard? (all needles would have fallen, mileage would have gone dark?)
- Misfire? - right before this started, i had a misfire code in cyl 3, but that was fixed after Fuel injectors replaced, issue could be stil there? but yet no codes, and no smell of gas.
- Oxygen? - new upstream and downstream O2 sensors, but maybe a vacuum leak? under stress would make it worse causing a choke, making the engine die?
- Fuel? - possible fuel pump failure? or bad Fuel pressure regulator? Needed at high speeds?
** also i have one of those OBD services (AUTOMATIC) where you can plug in and do various things. While this issue is happening, it is reporting that the car is "turning off" and "turning on" over and over. So when i drive say to work and never see/feel the issue, the dongle shows that i've taken 6 trips... but this may be a completely separate issue, so not considering it, but its information that out there.. **
Ok... i'm hoping you all can help me out on this one.. i'm an amateur with the tools, but willing to work through it if its within my skill set.. otherwise i'll take it to mech.
Thanks!