MY1PATH Posted December 4, 2008 Share Posted December 4, 2008 (edited) tonight I ran some errands, My pathy started up slow. HUH? after my first stop It started even slower and pulling outa the lot It suputterd @ 2800RPM. I pulled it over and free-reved it and it was as if it had a rev-limter set to 2800. to lay waste to my first suspision I pulled out the timing light and set it back to 15(what I'd been running for months) and tunred it off for a few min. It started slow but not as slow. I stopped by japanesse auto and the guy there said (inspite my experiment) it sounds like a MAF sensor. (he owns and loves an 89 HB, same TBI motor). b4 replacing anything he said to set the timing back (done) and unplug it for a few hours to re-set it.(In progress) It started up normal after that but still won't rev over 2800. This is a branch off of "advanced sprark timing for higer octane" but a new (hopefully unrelated) issue so new thread. I'm done with my Timing experiments untill I can prove its un-related. thanks, -jacobs Edited December 10, 2008 by MY1PATH Link to comment Share on other sites More sharing options...
Precise1 Posted December 4, 2008 Share Posted December 4, 2008 I'd unhook the battery, put the key in and turn it to run and step on the brakes a few times. (this is supposed to drain all juice from the system, I read it on some fanatic site somewhere). Have a beer, hook the battery back up and start it, let it get 1/2 warm and go for a nice mellow drive for the first 5 minutes, then start reving/stomping on it to see what it does. I'm sure you understand, but it is to make your ECU 'forget' and relearn the system. My guess is that you tweaked the timing too much and the brain was fighting it. No proof or backing in any manner, just a hunch. Hopefully I'm right, eh? Anyway, that is what I would do to start... B Link to comment Share on other sites More sharing options...
MY1PATH Posted December 4, 2008 Author Share Posted December 4, 2008 (edited) I'm sure you understand, but it is to make your ECU 'forget' and relearn the system. My guess is that you tweaked the timing too much and the brain was fighting it. No proof or backing in any manner, just a hunch. Hopefully I'm right, eh? Anyway, that is what I would do to start... B yup thats what I was thinking. Good Idea on the brake trick(learn a few things every day). Oh I just remembered, I'm gonna burn really rich again while my ecu re-learns my PYTHON injectors. It did that last time too. If this works, I'm gonna stick with 15 BTDC timing and 87/89 octane fuel. I have better ways to get allot more power planed for the future. Edited December 4, 2008 by MY1PATH Link to comment Share on other sites More sharing options...
edicer2 Posted December 4, 2008 Share Posted December 4, 2008 so did u figure it out? Link to comment Share on other sites More sharing options...
94extreme Posted December 4, 2008 Share Posted December 4, 2008 No proof or backing in any manner, just a hunch. ok, i'll call it a hunch too then.. :clears throat: Link to comment Share on other sites More sharing options...
MY1PATH Posted December 4, 2008 Author Share Posted December 4, 2008 (edited) so did u figure it out? well I tried the key and brakes with the battery out and either it didn't work, or something else is the problem. I thew in the towel for the night letting it sit till the morning unpluged, that should be more than enough. I seem to remember reading somewhere that on the tbi engine it does air/fuel based mostly on the MAF and some on the o2 sensor untill it reaches 2800rpm an then the o2 takes over. I don't remember where I read this, and it may have only been somones speculation but its a place to check. my o2 sensor is about 6 months old so unless its defective or pre-mature failure.... ahhhh! I'll just check some stuff tomorrow. Edited December 4, 2008 by MY1PATH Link to comment Share on other sites More sharing options...
MY1PATH Posted December 4, 2008 Author Share Posted December 4, 2008 hmm that sounds like the typical TBI problem (i think its maf I know theres been tons of threads on it) If thats the case maybe I'll splurge for the PYTHON MAF to go with my python injectors. I cleaned it a few months ago so I know it can't be dirty. Being that it still feels normal up to 2800, and there are no unusual sounds coming form then engine. do yall think its safe to to limp to work with it? 8 miles round trip 20-30mph and I normally shift @ 2g during this trip. Link to comment Share on other sites More sharing options...
unccpathfinder Posted December 4, 2008 Share Posted December 4, 2008 http://npora.ipbhost.com//index.php?showto...429&hl=2800 http://npora.ipbhost.com//index.php?showto...477&hl=2800 hope these help out... Link to comment Share on other sites More sharing options...
edicer2 Posted December 4, 2008 Share Posted December 4, 2008 so did u say it wasnt the MAF sensor? Link to comment Share on other sites More sharing options...
bitemedoughboy.com Posted December 4, 2008 Share Posted December 4, 2008 If thats the case maybe I'll splurge for the PYTHON MAF to go with my python injectors. I cleaned it a few months ago so I know it can't be dirty. Being that it still feels normal up to 2800, and there are no unusual sounds coming form then engine. do yall think its safe to to limp to work with it? 8 miles round trip 20-30mph and I normally shift @ 2g during this trip. get a FSM and run the ecu codes its that simple.... if the AFM is bad it will go into "limp" mode thats why it wont go over 2800 rpms Link to comment Share on other sites More sharing options...
MY1PATH Posted December 4, 2008 Author Share Posted December 4, 2008 so did u say it wasnt the MAF sensor?Its a possibility, I haven't ruled anything out. get a FSM and run the ecu codes its that simple.... if the AFM is bad it will go into "limp" mode thats why it wont go over 2800 rpms No CEL, No codes(55), and haven't been able to find a FSM for the TBI motor. Link to comment Share on other sites More sharing options...
bitemedoughboy.com Posted December 4, 2008 Share Posted December 4, 2008 (edited) Its a possibility, I haven't ruled anything out. No CEL, No codes(55), and haven't been able to find a FSM for the TBI motor. i bought one on ebay for 15 bucks its almost 3" thick, theyre priceless check the connector on the AFM, next step is to take it out and douche it with some AFM cleaner or rubbing alcohol. also try disconnecting your o2 sensor and see if it runs better Edited December 4, 2008 by bitemedoughboy.com Link to comment Share on other sites More sharing options...
unccpathfinder Posted December 4, 2008 Share Posted December 4, 2008 haven't been able to find a FSM for the TBI motor. theres a knock off version in the sticky's I believe...I have a hard copy that I may be willing to part ways with here soon since my TBI is no longer TBI Link to comment Share on other sites More sharing options...
edicer2 Posted December 4, 2008 Share Posted December 4, 2008 my freind has a 94 nissian quest with the vg30e in it and it has the exact same problem so if u figure it out let me know. we are going to put my spare MAF in there this weekend to see if thats the problem. It looked like it has new o2 seonsors so that shouldnt be it. I think its a MAF problem my z also did that and thatds what the problem was. all 3 of our cars have the same motor so i wouldnt doubt thats the problem. try to clean your MAF out Link to comment Share on other sites More sharing options...
MY1PATH Posted December 4, 2008 Author Share Posted December 4, 2008 (edited) I pulled the MAF and it looked ok exept the pulg, so I cleaned the contacts. anyway all back together battery in and it still has issues. base ON what I've read here I'm thinking the MAF is dead and its in "limp mode" I've called every parts store and they don't have one. anybody got one? the jy motors here are picked clean. the 4cyl tbi MAF should work too, same throttle body and parts.ROck auto had one.... There goes all the money for my FAL 180 Black Magic Extreme Fan. Edited December 4, 2008 by MY1PATH Link to comment Share on other sites More sharing options...
unccpathfinder Posted December 4, 2008 Share Posted December 4, 2008 I've got a complete intake off of an 87 if you interested I could sell it to ya at a pretty decent price and it should have everything on it...although I may not have the connector for the TPS if its on the main harness but if its on the engine harness i'll have it...you could shoot me a pic I can see if I have it. PM me if your interested in the full intake (i think the only thing missing may be a coolant temp sensor but i'm pretty sure its still there but not 100% sure) Link to comment Share on other sites More sharing options...
94extreme Posted December 5, 2008 Share Posted December 5, 2008 sine you don't have another maf to try, have you tried mode 5 of your ecu? Link to comment Share on other sites More sharing options...
MY1PATH Posted December 5, 2008 Author Share Posted December 5, 2008 sine you don't have another maf to try, have you tried mode 5 of your ecu? good call, I'll try that tomorrow b4 work. Link to comment Share on other sites More sharing options...
Kittamaru Posted December 5, 2008 Share Posted December 5, 2008 Mode 5? What's taht? Link to comment Share on other sites More sharing options...
MY1PATH Posted December 5, 2008 Author Share Posted December 5, 2008 Mode 5? What's taht?I think it checks MAF, TPS, and ignition systems. read the ecu self diagnostics post in the how-too's for more info. Link to comment Share on other sites More sharing options...
MY1PATH Posted December 5, 2008 Author Share Posted December 5, 2008 having second thoughts about my impulse buy of the MAF, If it is realted to my timing experiment I'm thinking It might be the crank angle sensor.... Link to comment Share on other sites More sharing options...
Precise1 Posted December 5, 2008 Share Posted December 5, 2008 Possibly? I'd do as much diagnostics as possible before purchasing anything... B Link to comment Share on other sites More sharing options...
Terrano1992 Posted December 5, 2008 Share Posted December 5, 2008 No CEL, No codes(55) I had the same trouble 2 years ago. No CEL, code 55, but engine revs only up to 2800-3000rpm. Detailed examination found the culprit. There were short circuit in ECM harness (exactly - part of harness in passenger footwell, under the carpet). One wire (TPS power supply) had faulty insulation and was shorted to the ground. As a result - no power (+5 volt) on TPS, no feedback signal from TPS to ECM. One piece of electric insulation tape, 15 minutes of work (diagnostic time is not included) , and my truck was recovered. This case is not described in FSM. When you press accelerator, ECM thinks "throttle isn't opened, but engine spontaneously revs up" and temporarily cuts off fuel injectors for safety (I suppose). Maybe you have the same trouble... Link to comment Share on other sites More sharing options...
94extreme Posted December 5, 2008 Share Posted December 5, 2008 having second thoughts about my impulse buy of the MAF, If it is realted to my timing experiment I'm thinking It might be the crank angle sensor.... i think that maybe mode 4 on the ECU. Link to comment Share on other sites More sharing options...
MY1PATH Posted December 5, 2008 Author Share Posted December 5, 2008 ran mode 5 2x for 5 min reved it till it limited itself up but no indication from the ecu. Pulled out the seat, pulled out trim and carpet, pulled out ecu and checked all wires from the ecu to the firewall not shorts there. Ran mode 4 to check the TPS. TPS checked out fine but.... Drive the vehicle with the ECU unbolted and within view. Make sure the GREEN LED turns on when speed is 12 MPH or more. If not, check or replace the Vehicle Speed Sensor.the green led did not come on over 12MPHNo with the 89 I thought the speed sesor was mechanical so does this apply? or is this the sorce of my problem? Link to comment Share on other sites More sharing options...
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