subynut Posted June 15, 2005 Share Posted June 15, 2005 I just finished putting in a new o2 sensor in me suby. Also got the A/F guage working. I've been watching the A/F guage: during cruzzing, it's bouncing between off the scale lean to just in the rich. During accelleration, it's still bouncing till about 4500 and then it sits just a little rich till I decide to shift. So, here's my question: while I'm accellerating, it's shuddering when the A/F is lean from about 2500 to 4500. After that, it pulls good past redline. Is it supposed to do that? Also, the guage is a SunPro from Autozone. Not the most expensive unit, but it gives me an idea. Link to comment Share on other sites More sharing options...
TurboSPFI Posted June 15, 2005 Share Posted June 15, 2005 o2 sensors are made to have a "swing", this is the rich/lean swing as you describe. By having voltage vary from 0.00 - 0.999, it bounces from rich (0.99 volts) to lean (0.00 volts) to aquire an average 0.45 volts, equivelant to 14.7:1 stoichiometric ratio. Link to comment Share on other sites More sharing options...
subynut Posted June 15, 2005 Author Share Posted June 15, 2005 Ok, that explains alot. BUT, why does it hang out so far into the lean area? That's when my power goes splat. If it's in the upper end of the ideal, my power is more smooth. Could it be the coolant temp sensor is off a bit and causing the ECU to run just too lean? Since it's running just a little rich during the upper end of the rpm range, I don't think the fuel pump or regulator is bad. I would think as you climb up in the rpms you would have less and less fuel. Or am I just off on a wild tangent? This hesitation is driving me nuts! Link to comment Share on other sites More sharing options...
archemitis Posted June 15, 2005 Share Posted June 15, 2005 bouncing at part throttle is good. when you floor it it should go pretty far into the rich, and stay there when you keep it floored. if it doesnt stay steady at wot, and it still bouncing, somthing is wierd. hows your timing? any trouble codes? did you reset the computer after the o2 instal? my spfi was always a bit on the rich side. but it was almost as fast as my xt6 motor for some reason?! pulled real hard. i advanced my timng alot too. Link to comment Share on other sites More sharing options...
subynut Posted June 15, 2005 Author Share Posted June 15, 2005 Timing's about 22 deg. She idles a little rough. Vac is about 12"/hg (that is the proper label, right?) and no flutter. Doesn't go steady rich till 4500. And it's just barely into the rich. CEL is off, however I did not rest the ECU. I'll see if I can figure out the FSM's procedure on resting the ECU. Now, this might be relevent: During warmup, when the engine temp gets to 160, the idle starts bouncing from 1200 downto 700, then back up again. Does this about 15 times then the CEL comes on with a code for the air control valve and idles rough at about 1100 rpm. If I shut it down, and restart, it still idles rough, but the CEL is off. O2 sensor has not warmed up yet, so I don't know what the A/F ratio is. Link to comment Share on other sites More sharing options...
TurboSPFI Posted June 15, 2005 Share Posted June 15, 2005 u might just have a p.o.s. gauge Link to comment Share on other sites More sharing options...
subynut Posted June 15, 2005 Author Share Posted June 15, 2005 There is that possiblility. Link to comment Share on other sites More sharing options...
archemitis Posted June 15, 2005 Share Posted June 15, 2005 that vac number seems low. i think mine would suck down to about 18 at idle? hope someone else can chime in here, i can look at my xt motor, its close to 20 as far as i can remember a vac leake wouuld cause wierd problems. or a bad iac valve, letting in air when it shouldnt. Link to comment Share on other sites More sharing options...
subynut Posted June 16, 2005 Author Share Posted June 16, 2005 Yeah, with the Weber I was running about 16"/Hg. Ok, I checked the codes as per the FSM and I had two: o2 and the Air control valve. Cleared the codes and went for a test drive and made no difference as I figured. Anyways, I checked the impedence of the air control valve and I read about 29 ohms. Acording to the FSM, it should be between 7.3 and 18 ohms. I think I found a problem. Looks like a trip to Tucson is in order. Anybody know what those go for new? Concidering this is my second J/Y valve, I think I'm going to bring an ohm meter with just so I can test it before I buy it. Link to comment Share on other sites More sharing options...
subynut Posted June 16, 2005 Author Share Posted June 16, 2005 IEEEEEEEEEE!!!!!! Just got off the phone with the stealer. They said 400 bucks for one of those Air control valves! Me thinks it's gonna be a run to Tucson some time next week.:-\ Link to comment Share on other sites More sharing options...
subynut Posted June 17, 2005 Author Share Posted June 17, 2005 Man, I hope the Air control valve is the problem. That car of mine runs really lean with temps in the mid 90s. Very annoying............. and I aint gonna get to fix it till mid next week! AAAAAAAAAAA:banghead: Link to comment Share on other sites More sharing options...
Cougar Posted June 17, 2005 Share Posted June 17, 2005 I doubt that the resistance you read is really a problem. I can't say this for sure but that is what I think anyways. You should be able to test this device by applying 12 volts to it and see if it opens or closes the the air passage. Link to comment Share on other sites More sharing options...
TurboSPFI Posted June 18, 2005 Share Posted June 18, 2005 i wouldnt go the air control valve route... i think your wasting your money. Link to comment Share on other sites More sharing options...
subynut Posted June 18, 2005 Author Share Posted June 18, 2005 ok......but I can't afford a new one, I'll hafta find a used one out of the junkyard. Besides,if it aint the air control valve, what else could it be? Coolant temp? Maf? tps? ecu? Fuel pump? That's the only thing that kicks on the CEL for a short time during warmup. It's also logical, the other posibility, I suppose, is the coolant temp sensor. She's running very lean when the air temps are in the 90's+. Nots a good combo for long desert driving. If I accually get to goto WCSS this year, I gots a LONG run though the nevada desert where there is no place to get parts for miles. Also, being a moble comp tech, I use my suby all the time. I really don't think the engine is supposed to run so close to the point of fuel starvation. I live in a hot, dry, and high elevation climate. The sensors and devices have to be within they're specification; otherwise the engine goes nuts. My hitachi carby ran some what lean during cruzing, then would go rich when I stood on it. My weber did the same thing. Why does the SPFI do this? Somthings not right and the computer is telling me nothing. Link to comment Share on other sites More sharing options...
subynut Posted June 22, 2005 Author Share Posted June 22, 2005 Figured I'd give you guys a heads up. Tried swapping the MAF and the Air Control Valve with the ones in my brother's 87 wagon. Made no difference in my Suby and no change in my brother's Suby. So, I just cleaned the Air Control Valve with some carb cleaner (the plunger felt a little sticky) and adjusted the throttle linkage (wasn't opening all the way) and she seems to be running better. Accually goes to rich during WOT now! Still low vac and rough idle, but improved. I was thinking that maybe it's the cams that's causing the rough idle. Don't know. I'll see tomarow in the 95 degree temps if I've improved anything or not.:-\ Link to comment Share on other sites More sharing options...
Cougar Posted June 22, 2005 Share Posted June 22, 2005 Thanks for the feedback on the sensors Subynut. That is good to know. Have you checked for a leak at the intake manifold gaskets? Link to comment Share on other sites More sharing options...
subynut Posted June 22, 2005 Author Share Posted June 22, 2005 No, I'll check those out later today. I have rechecked the torque on them and they havn't moved, so if they are leaking some, it may be they just need to be replaced. When I did the conversion to SPFI, I didn't put new intake gaskets on because they were new when I put the new engine in a few months back. Maybe I should've. Link to comment Share on other sites More sharing options...
subynut Posted June 24, 2005 Author Share Posted June 24, 2005 Ok, I checked out the intake gaskets and didn't find any leaks. Strange...me Suby is happy when the temps are below about 85. No hessitaion whatsoever. But as those temps climb, boy, does that car complain: "I don't wanna! I don't wanna! I don't wanna! " Crazy Subaru. On a side note, every once in a while, I'll get a good and loud backfire through the intake when I initally step on the gas. It only shows up when the temps are in the upper 90's. Link to comment Share on other sites More sharing options...
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