Couple small problems left with my car I need to sort out

[gsxbig16g]

I have a 98 GSX built motor, big 16g, DSMLINK V2.5, and all the necessary bolt ons.

Problem #1:When car warms up, the idle rises to 1500rpm for a few seconds, then drops to 1000rpm for a split second, then works its way back up to 1500. It does NOT overheat, and it drives fine, just will not idle right. (replacing idle air controller this weekend is that the issue?)

If the car isnt fully warmed up yet, it idles where it should, but once the coolant is warm and it should go into closed loop mode, it starts revving up.

I dont know if this has anything to do with it, but if you just baaaarely push the gas pedal down the car acts like its going to rev up a little like it should, but then it just dies out and the rpms drop under 800 like its gasping for air, this cycle repeats every second as long as you baaarely hold down the gas pedal. If you give it anything more than 5% throttle, the car acts normal and revs up just fine. SO WEIRD!


Problem #2: In every gear when I floor it, I only get 10psi of boost until 5000rpm, then boost kicks in anywhere from 16-26psi!

The weird part is when my boost gauge and greddy boost controller are reading 10psi, dsmlink still reads negative PSI, but after 5000rpm, the numbers on my log match up to the numbers on my gauges??

Problem #3: when I look at my dsmlink log, O2 sensor voltage never moves, just stays at 0.04V constant, I replaced the front O2 and still same problem.


Anyone have any ideas? Car goes in to a master tech on saturday for a new master cylinder (mine is leaking), so I will ask him to take a look. but i figure maybe my issues are common dsm issues you guys might know about?

Any input would be greatly appreciated.

 

[Eclipse2630]

I have a 98 GSX built motor, big 16g, DSMLINK V2.5, and all the necessary bolt ons.

Problem #1:When car warms up, the idle rises to 1500rpm for a few seconds, then drops to 1000rpm for a split second, then works its way back up to 1500. It does NOT overheat, and it drives fine, just will not idle right. (replacing idle air controller this weekend is that the issue?)

If the car isnt fully warmed up yet, it idles where it should, but once the coolant is warm and it should go into closed loop mode, it starts revving up.

I dont know if this has anything to do with it, but if you just baaaarely push the gas pedal down the car acts like its going to rev up a little like it should, but then it just dies out and the rpms drop under 800 like its gasping for air, this cycle repeats every second as long as you baaarely hold down the gas pedal. If you give it anything more than 5% throttle, the car acts normal and revs up just fine. SO WEIRD!


Problem #2: In every gear when I floor it, I only get 10psi of boost until 5000rpm, then boost kicks in anywhere from 16-26psi!

The weird part is when my boost gauge and greddy boost controller are reading 10psi, dsmlink still reads negative PSI, but after 5000rpm, the numbers on my log match up to the numbers on my gauges??

Problem #3: when I look at my dsmlink log, O2 sensor voltage never moves, just stays at 0.04V constant, I replaced the front O2 and still same problem.


Anyone have any ideas? Car goes in to a master tech on saturday for a new master cylinder (mine is leaking), so I will ask him to take a look. but i figure maybe my issues are common dsm issues you guys might know about?

Any input would be greatly appreciated.

as for problem number 1 i had the same issue, my buddy adjusted my IAC. i actually met him on here, and come to find out he lives right down the road from me. he adjusted the iac. try adjusting yours before you assume its bad. maybe it was just outta wack like mine. if adjusting it dont fix it then replace it. if it still acts up i would search further.

as for problem number 2, as most say check for boost leaks and where are all your vacuum lines running too? are they correct?

problem number 3, no clue i dont have link

 

[BurrowZ]

I'm going to guess problem 1 and 3 are directly related. An o2 not cycling usually means a dead o2 sensor, but since it's a new one, is the harness messed up?

.4 is a generally stoich reading for an o2. I'm not positive on DSMs but on other vehicles if the o2 is disconnected or not present the ECU will take a default reading of .450 and base its fuel maps off of that. Basically a limp mode.

Are you lean at idle? Rich at idle? Have you properly set your idle?

As for your boost issue I'd like for someone to chime in as I'm having the same problem.

 

[Eclipse2630]

it just hit me, for the reving thing, check your coolant temp sensor, i remember reading on that if your coolant temp sensor is bad it messes with things similar to your issue.

as for the o2 sensor like the other guy said, if you have a obd2 reader it should tell you if your o2 sensor is bad. If you dont have a obd2 go to advanced auto and they will run codes, thats if you have cels.

 

[gsxbig16g]

it just hit me, for the reving thing, check your coolant temp sensor, i remember reading on that if your coolant temp sensor is bad it messes with things similar to your issue.

as for the o2 sensor like the other guy said, if you have a obd2 reader it should tell you if your o2 sensor is bad. If you dont have a obd2 go to advanced auto and they will run codes, thats if you have cels.

already replaced my coolant temp sensor 2 weeks ago, didnt fix the problem.

The o2 sensor is brand new, its not even a week old yet. And i have a dsmlink, usually the only code I get is unable to go into closed loop mode.

 

[97gst_spyder]

That idle surge is caused by quite a few things. O2, BISS adjustment, TB Seals, vacuum leaks, bad isc, etc.

 

[turbo98eclipse]

Sure you dont want to replace that master cyl yourself? Its quite easy and straight forward -- could save you some money!

 

[gsxbig16g]

Sure you dont want to replace that master cyl yourself? Its quite easy and straight forward -- could save you some money!

I already had the master cylinder replaced on saturday at the dealership, I know one of the master techs there, he charged me $60 .

I bought another throttle body, and a new gasket, and another IAC, I'm just waiting for somoene to try and adjust my IAC before i put the new one on. I have no idea to adjust it, so i guess maybe I'll ask the guys at alamo autosports to try and fix it when they tune the car this week.

honestly my biggest concern right now is the boost issue. I hit only 10psi in any gear up to 4500 rpm, then after 4500 rpm i get between 16-20psi with a 26psi peak boost recorded!!

 

[Eclipse2630]

I already had the master cylinder replaced on saturday at the dealership, I know one of the master techs there, he charged me $60 .

I bought another throttle body, and a new gasket, and another IAC, I'm just waiting for somoene to try and adjust my IAC before i put the new one on. I have no idea to adjust it, so i guess maybe I'll ask the guys at alamo autosports to try and fix it when they tune the car this week.

honestly my biggest concern right now is the boost issue. I hit only 10psi in any gear up to 4500 rpm, then after 4500 rpm i get between 16-20psi with a 26psi peak boost recorded!!

my buddy has this problem even after he replaced his master cylinder as well. He put an external dump on and his boost creep issue went away.

 

[gsxbig16g]

Ok I adjusted the BISS screw and now the car idles perfect! The only 2 issues remaining are O2 sensor and Boost.

I just put a new O2 sensor in, in my dsmlink log the voltage always stays at .04 volts. The old o2 sensor read the same value. If i unplug the sensor I get the same readings. Im guessing my o2 harness is bad?

I had my greedy profec b 2 tuned and still no luck with boost. The higher i turn the gain up on my boost controller, the higher the boost goes AFTER 5000rpm. But no matter what I do, the boost stays at 10psi through 4500rpm. I had the waste gate actuator checked and its working perfectly. Also haven't found any boost leaks. There is a vacuum hose that isn't plugged into anything, it comes from the passenger side of the fire wall, have no idea what its for.

 

[Eclipse2630]

Ok I adjusted the BISS screw and now the car idles perfect! The only 2 issues remaining are O2 sensor and Boost.

I just put a new O2 sensor in, in my dsmlink log the voltage always stays at .04 volts. The old o2 sensor read the same value. If i unplug the sensor I get the same readings. Im guessing my o2 harness is bad?

I had my greedy profec b 2 tuned and still no luck with boost. The higher i turn the gain up on my boost controller, the higher the boost goes AFTER 5000rpm. But no matter what I do, the boost stays at 10psi through 4500rpm. I had the waste gate actuator checked and its working perfectly. Also haven't found any boost leaks. There is a vacuum hose that isn't plugged into anything, it comes from the passenger side of the fire wall, have no idea what its for.

that vacuum line on the passenger side, did you trace it down to something? Is there a vacuum line on your egr valve?