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93 Sentra SE-R. Uses too much fuel and has half the power it should?
i have been thru alot of threads and a few different forum sites and just about exhausted my search for a fix for this car. when i bought it it ran and drove but i could tell it wasnt advancing the timing like it should as i drove because at a certain point in the throttle it would bog down while driving. if i gave it just enough throttle it would accelerate just fine. so far these are a few things i have done to it: new distributor cap and rotor, new spark plugs, plug wires look good, removed EGR valve and cleaned it as well as the "BPT" tube, i checked voltage at the MAF and it was too high so i regrounded it and got it back to specs, tested the TPS voltage and it was in spec closed and at WOT, checked timing with TPS unhooked and, with the distributor as far advanced as i can get it, i cant get anywhere near the 15 or 17 degree mark...was thinking maybe the timing chain jumped a tooth? just today, and after the above attempts at fixing my problem, i removed the entire intake manifold, took it all apart, cleaned out all the gunk in the "collector" as well as inside the intake runners and removed the IAC valve, took it apart, and cleaned out what gunk had built up which wasnt much really. i honestly think i wasted my time removing the intake manifold but it cant hurt i guess. this is my first time doing anything other than a head gasket and minor tune ups on anything with less than 8 cylinders. always been a chevy big block or cummins diesel kinda guy. thought maybe id try and get a few more miles to the gallon and maybe a little power too with this car, so far its not lookin too promising though. any help at all is greatly appreciated, thanx!
See if you can borrow someone's chipped ecu and turn off the knock sensor. You may have a bad knock sensor or wiring to the knock sensor. It happened to me, symptoms just like you say.
Another thing to check - how old is your oxygen sensor? Maybe upgrade it to a Bosch 15727 4-wire sensor. If your exhaust header is rusty then it won't allow the stock oxygen sensor to get grounded very well. The Bosch 15727 has that extra ground wire that you can run to the intake manifold, just like the factory ground wires are located there.
Edit: also look to see if your crank pulley is separated. A separated pulley will change your timing and won't allow you to set it right.
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Last edited by oldman; 06-18-2011 at 06:31 AM.
Reason: mention crank pulley separation
Hey thanx for the reply! Im goin to the parts store today to finally get the gaskets to put the intake manifold back together and back on the car. Parts stores around here are terrible in the intelligence department lol. Ordered me the wrong stuff like twice. The oxygen sensor definitely appears to be 1993 material and the exh manifold is for sure rusty. Ill definitely pick up a 15727 today just in case. As far as the knock sensor goes i have ***** to borrow an ecu from but is there a way i can check voltage on it and the wiring? Ill check out that crank pulley today but if it was saparated, wouldnt it not spin the engine accessories very well if at all? Cant tell ya how much i appreciate your input! Thanx again!
Alright so the intake is now back on the engine after a thorough cleaning and all new gaskets. Everything is hooked back up and after taking the car up the road the first thing i noticed is the same problem and symptoms as before i started. Back to square one. However while the intake was off i did purchase a chiltons manual and read about the knock sensor. It said that, with an ohmmeter, and the positive probe on the 'A' terminal and the negative probe on a good engine ground, as long as it has continuity the sensor should be good. It had continuity just like the manual said it should. They had to order the bosch 15727 so i havent tried the groundong of the o2 sensor yet but it just seems to me that the car is struggling to accelerate like its not advancing ign timing appropriately. As far as i can tell the balancer isnt separated so IDK. Parkin it for the time being and wastin some gas with the big block. Lol.
copy on drinkin. lol im bout there myself. i had this crazy idea today that it might have been the MAF sensor so i dismantled it in its entirety and used the proper cleaner provided by advance auto parts. let it dry and put it back together, drove the car a few minutes ago and SUPRISE SUPRISE its still does the same damn thing it did begore i wasted 30 min of my time haha. i guess the only things i havent done is tried putting in the o2 sensor "oldman" recommended and checking to see if the mating marks on the cam gears line up with the ones on the chain. after i do that and if it doesnt fix it, itll be in the yard with a for sale sign! ive got way too many projects to be dwelling on just this one. its got a good deal of rust on the body but ive put a ton of new parts on it and the interior is nice minus the sunroof not working for anyone that may be in the market for one.
Do you have a code reader? If not can you limp it to an Autozone, O'Reilly's, etc. - they read codes for free:
11 = cam position sensor
12 = MAF
13 = Eng. Coolant temp sensor
14 = Vehicle speed sensor
21 = ignition signal
31 = ECM
32 = EGR
33 = Oxygen sensor
35 = EGR temp sensor
43 = TPS
45 = injector leak
55 = no malfunction
Does it start and idle normally?
Check for vacuum leaks, intake leaks between MAF and throttle body.
Check fuel pressure:
- At Idle: Approx. 245 kPa (2.45 bar, 36 psi)
- A few seconds after ignition switch is turned from OFF to ON:
Approx. 294 kPa (2.94 bar, 43 psi)
Check injectors. With engine off, key off, should be 10-14 Ohms resistance between the 2 terminals on the injectors.
Jp314, i cant thank u enuff. Thats alot of things that i havent tried and i appreciate the info greatly! I have to work the next 3 days but ill give it another shot and hopefully find the problem soon. Ill keep progress poste on here. Thanx again!
Yuh i still have the same problem with my newly built motor in a 95 b14. Ive checked everything.. used specs from the haynes manual. Im a tech in orlando n cant find any help. When i plug in the scanner it has no codes but on the emissions lights has three red,yellow,green.. mine is on yellow. I had a code a while back from the o2 sensor n replaced it. i cant figure this out. help anyone one please..lol
Aint been on here in awhile, thot id see if anyones had any new thoughts on a possible fix for my ongoing problem. The cars still holdin down the same spot in the garage and still has the same problem. I start it from time to time but i work so much its been hard to find time for it lately. Id still like to see it fixed and use it as my dd. HELP ME!!!! Lol.
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