2000 2.5RS Constant Hesitation

Iboc_C64

Iboc_C64

New member
Ok guys, looking for some hints as to where to start on a problem my brothers 2000 2.5RS is having. First let me tell you where we stand with it. We bought this from someone here on the forums in a bit of a beat up condition to fix it up. My brother ("Vertigo101" on here) has had all the safety, maintenace and operational issues fixed. He also got all the cancerous rust fixed and replaced the rocker panel. We finally got the stock exhaust put back on to make it quiet enough to drivable. It still sounds a little funny and I'm wondering if the "high flow cat" that is supposedly on it is possibly punched out. It also has an Injen cold air intake and the AC compressor was removed before we bought it.

Anyway I took it out for a drive and it seems to have gained some low end torque from fixing the exhaust but now the hesitation in the higher RPMs is more prominent. It feels at low RPM like it is gonna take off better than my WRX until it hits about 2000 RPM, at which point it starts climbing RPMs noticeably slower and as you climb higher it feels like its in a tractor pull carrying a heavier and heavier load. At 4000 rpm it almost doesn't want to climb anymore. I hear this pop/tap noise from the engine bay on the passenger side, maybe backfiring or engine knock? It could be emanating from the intake inside the fender. It picks back up in power at about 5000 but continues to ping or pop lightly in the passenger side engine area. Almost sounds like small stones hitting the inside of the mud guard or something. All this and it throws no CELs. I was thinking plug wires, plugs or coils. Maybe a sensor problem somewhere. Any ideas?

 
jaKe

jaKe

>>><<<>>><<<
Cam timing too advanced? Sound is spark knock or detonation?

 
wzrd

wzrd

New member
Not sure but one of my older subies have 2 fuel filters that used to get clogged every few months..Bad fuel filler neck was letting crap in.

 
Iboc_C64

Iboc_C64

New member
Hmm. If it was the O2 sensor though it would throw an O2 CEL or a Catalytic Converter efficiency CEL wouldn't it? Im kinda wondering if this thing actually has a bulb in the Check Engine Light location. Sorry about posting a near duplicate thread to Vertigo's guys. I forgot to tell him I was going to post about it after I talked to him about it.

 
B

brighton

Rally Fluffer
Iboc_C64 said:
Hmm. If it was the O2 sensor though it would throw an O2 CEL or a Catalytic Converter efficiency CEL wouldn't it? Im kinda wondering if this thing actually has a bulb in the Check Engine Light location. Sorry about posting a near duplicate thread to Vertigo's guys. I forgot to tell him I was going to post about it after I talked to him about it.
Click to expand...
Any AutoBone will scan your ecu for free. We all need tobStop e-diagnosing and get some Real answers. Then post up what codes show up and then we all will have a better idea of what's going on.

 
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M

Matt

Well-known member
It will eventually when the computer detects the issue enough. When mine went bad it took almost 3 weeks to finally throw the code.

 
Iboc_C64

Iboc_C64

New member
Ok, hows about an update! I was working on the dash lights in my old Grand Am and I needed to go to town for some bulbs. I decided to take my brother's car. I got his permision and popped open the hood on his car and methodically disconnected the wire harness connectors from every sensor, blew them out and reconnected each one, one at a time. I also pressed all the spark plug connectors on to the plugs & coil and finally I found a kink in a large piece of rubber tubing connecting the air intake to another tube behind/beneath the throttle body. After those quick adjustments I took it to town for the bulbs and viola! It appears to have gotten rid of most of the problems that were ailing it except for the off an on high RPM hesitation, which comes and goes at random, but is there most of the time. I believe that to likely be an O2 sensor. Some of the other sensors may be sticky too and so I will attempt to clean them, then once we can get a scan tool I can check for any stored codes. So far no CEL light yet. Interesting note, we noticed that the Highbeam indicator light flickers, which makes me wonder that if the CEL where triggered would it even illuminate? Guess we need a scantool to find out.

 
M

Matt

Well-known member
do a self check...turn the key on and see if the bulb illuminates properly....that hose you found goes to the pcv valve, the other two hoses off the intake go to the valve covers....subaru has a tsb out specifically for the 02 sensor cracking.

 
Nigel Prodrive

Nigel Prodrive

Dirt surfer
check resistance on plug wires. my RS Snowball had a nagging misfire for weeks, tried all sorts of stuff (coil pak, fuel filters, sensor checks etc), finally a garage checked the plug wires and boom one had super high resistance.

never considered wires as potential prob, they were pretty new, about a year old.

go figure.

 
Iboc_C64

Iboc_C64

New member
Thanks Matt, will do as soon as I get home unless Vertigo sees this and tries it himself. It ran really nice, but for some reason it struggles to get past 80mph and Im pretty sure it should do better than that. Then again its tires are oversized so maybe that is part of the problem and it is going faster than I think. Ugh, gonna take some time to get use to all the quirks of the previous mods.

 
Iboc_C64

Iboc_C64

New member
Ok guys, I have an update. There is no bulb in the CEL socket on this car, so someone was lazy. Dan came over last night and we used his Mac Laptop to connect to the OBDII port and pull the codes. Unfortunately Dan (RangleyRallyDG) and I did not think to write down the P#### codes before clearing them, but it had about 6 of them. I was able to retrieve some info after the codes threw again during our test drive, but it did not throw them all. The codes that it threw almost instantly were something like "H02S HEATING SYSTEM VOLTAGE BANK 1, SENSOR 2, LOW" and "O2 SENSOR SHORT TERM FUEL TRIM". I believe the second one was for 02 sensor #1 IIRC. There was at least one "SPEED SENSOR" code and some other data. There was a tab for testing or something and it returned data saying "EVAPORATIVE SYSTEM INCOMPLETE" and "O2 SENSOR SYSTEM INCOMPLETE". It may not have said exactly that but it was close to that. Dan also said that it said something about running in "OPEN LOOP" mode the entire time do to engine load or something like that. I wish I took down the P#### codes but we missed them. After some research though it looks as though he needs both O2 sensors. It may have had a "Baryometric Pressure Sensor" error too but I got that one when I tested my Grand Am and I don't know if I am confusing the 2 because the Grand Am had a front O2 and MAP sensor errors. Guess I should not have tested one right after the other, my memory isn't as sharp as I thought.

 
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Iboc_C64

Iboc_C64

New member
I was just thinking, if the system was in open loop the whole time like the computer said, shouldn't the engine be running great aside from a little rich? This thing runs like crap at the top end of the RPM range where it should be running mint if it was just the 02 sensors. Any Ideas as to why that would happen guys? Above 4000 on this car the is a near TOTAL loss of power.

 
Iboc_C64

Iboc_C64

New member
How do I check them? I have always just replaced them. Can I use the resistance function of a multimeter to check them?

 
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