PO170 (1 Viewer)

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Hi Everyone,

:princess:'s 80 threw a PO170 and would not run worth hoot for a minute or 2 today. Anyone know what's up?

Thank you,
 
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:princess:'s 80 threw a PO170 and would not run worth hoot for a minute or 2 today. Anyone know what's up?
Your '95 is the year that Toyota transitioned to OBD and is not fully OBD-II compliant so the reader might be interpreting the code or the ECM might be giving a '95 "only" code. The list that Beno posted is for a 1997 which is fully compliant with the OBD-II codes.

Other years and makes show the P0170 (using Google) to be related to fuel trim and basically says that it is a fuel trim malfunction. That doesn't tell us much as you would expect a "too lean" or "too rich" code so that is why I think you need to reference your 1995 FSM and find out what Mr T intended for a P0170 code (BTW, it is Pea-zero-one-seven-zero; you typed pea-oh-one-seven-zero ... helps if you google for the right term.)

I did a word search on the complete FSM for a 1997 and there is no P0170 code in the entire manual.

-B-
 
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I just finished erasing the same code on my LX, based on my Innova 3130 Scanner P0170 means = "fuel lean mixture on bank one". I had the scanner erase the code, and no more check engine light for the last 15 minutes.
Although, I believe it was my fault the engine code showed up. I filled up the rig, with the engine running, after the rig drank all 20gallons of 91octane, the check engine light was on. But honestly, I couldn't tell any difference, the rig was running as good as usual
 
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I would carefully look at the wiring going to O2 sensor #1 (pre-cat)
I would not replace that O2 sensor based on that code though. The running bad is what makes me suspect bad wiring.
-B-
 

jfz80

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bump to the top..... Just got to GSMTR and was welcomed by the same code and rough running when pulling light to medium load at 2k rpm. It occurs when holding speed, not accelerating, at 2k rpm and feels like it misses or dies momentarily at random intervals, second and third gears esp. Ive looked at the wires to 02 sensor and the outer sheilding is melted where the bundle goes over the frame and right under the rear heater lines. I might have done this today as the hills had me pushing 205 and i ran the rear heater on high to keep the temps down. The individual wires and insulation look fine however.

at crawford's w/ a signal for the moment....any other thoughts.

I have had a history w/ the TPS and IAC extensions for the supercharger, but after rewraping last summer i havent had any problems and they do not seem to be touching or obviously melted anywhere along their lengths.
 

landtank

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Jason, I think your problem is with the MAF connector pins. I've had a few different issues lately with them. What you need to do is pull out each pin in the connector and bend the little leaf spring that makes contact with the other side so it is tighter.

You might also try cleaning the sensor as the one used in my housing is a little more sensitive to dirt.
 

jfz80

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Oh man oh man i forgot how fun broadband is :D Thanks for the tip Tank!
Yep, meant to mention I was running the LT MAF sensor. I looked at the TPS and IAC extensions and manipulated them while running looking for fluctuations and found none. Will take a look at the pins in the AM. Thanks guys.
 
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if that is an check engine code its a misfire in the #1 cylinder. this could be an injector or a bad plug or both. but its definitly #1 cylinder check that. ODB-II didn't come out till 96 thats OBD-I code
 
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jfz80

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Alright worm... if you are gonna throw out daunting info like that I'd love to hear a lil more about it.

Have you had experienced this issue? Not doubting at all..... and I surely dont want it to be misfire, but it is exactly what it feels like but the code reader pulls 170 and scrolls... heated bank 1 running lean.

Just curious where you came about the info and what experience you had with it. Most the 95 cruisers are OBD-II compliant actually and I have the scanguage hooked to the diagnostics port. Since it is the transition year Beowulf was explaining thats why it was a generic 170 and not specific 171 (lean) or 172 (rich)


Now I did clean the MAF (it was nasty) and bent the pins to make for a tighter contact and it had no affect on the situation.

wires and plugs are 20k miles old and dont know about the dist/cap/rotor. o2 sensors may be original for all i know and it definately looks like #1 is well rusted in place. I had been thinking this would be my next step on the road to recovery. Any thoughts? Beo.... I checked all the wiring again from the split in the harness to #1 and they all look great.

did you say sensitive to dirt? this is after one year and < 15k miles
GSMTR09 035.jpg
 
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landtank

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Jason, that is the IAT sensor and not the hot wire MAF. Did you clean those as well? If you look up inside the tube you will see two small wires side by side. I spray them down with MAF cleaner and use a small artist brush (model paint brush) to gently sweep the crap off of them.
 

jfz80

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Ok Rick, you got me.....;)

But now i have cleaned the hotwires, removed and tweaked the pin connectors and I still have a somewhat consistant miss at 2200 RPM under very light load. I pulled the outer sheathing on the O2 sensor wires and inspected each wire visually and twisted as it was running to try and replicate the issue to no avail. Next would be an OHM meter just to be more scientific about the process i assume?

Also manually checked the IAC and TPS cable harnesses while running to try and replicate the issue as well w/ no results.
 
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Hi Everyone,

Last week it started back firing when it starts so I cleaned my MAF. It is still having the same problems.

Any ideas on what to look at next? I'm thinking fuel filter and VSV.

Thank you,
 
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Hi there,

I''m new here, and joined just to reply to this post.

I have been fighting a P0171 for a few months and finally traced it to a weak fuel pump. Tried all kinds of stuff before that - multiple maf's, fuel filter, wires, plugs, new injectors all to no avail.

The leanness will characterize on a scanner as high long term fuel trim and low front 02 voltage. Voltage might even peg near zero for some time whilr ltft is max'd. If you reset the efi by pulling its fuse, the vehicle may run very badly because the reset keeps ltft at zero for some amt of time. During this period, the engine will run very lean because it isn't getting enough fuel.

In my case, a quick fix was to bypass the fuel pump resistor and run full voltage all the time. I have no idea how to actually do that, but others on here probably know how.

Just wanted to share my experience. This was the hardest problem to diagnose. A scanntool that can create data logs and graphs is really helpful for this sort of problem. If you can get one of those, post a graph of load, st and lt trims, and fr o2 voltaqge.
 
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Attached is a scan showing the operating parameters when problems occurred. Load ramps up, and the engine goes into this rhythmic miss. Feels like a bad plug wire. Notice the ltft is max'd and the o2 is way lean.
o2_ft_load_tp.jpg
 

landtank

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well if a weak pump will do this then the first check I'd do is swap out the fuel pump relay. They have been known to give the trucks starting and running issues in the past.
 

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