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View Full Version : For the love of all things Toyota, please help!



GreenRiverBoy
04-07-2016, 09:49 PM
Been a long time lurker here and have been able to keep my Previa operational by just reading past post but now have problem beyond me.

I have a 94 Previa SC with 215,000. I had not driven it much this last year and took it out for about 30 miles and on my way back home is when the problem started. During the trip back home, it started missing and running very rough. Felt just like an ignition issue to me. At idle it would almost die and if you hit the gas it felt as if it was "bogging" down. Like it was not getting fuel or air or maybe running too rich. The only way I got home was by barely giving it just enough gas to stay at a slow constant speed.

That was about 2 months ago and it has sat since then. Today, I replaced the spark plugs (autolite APP-3923 gapped at .043 torqued to 20ft-lbs), ignition rotor and distributor cap, fuel filter, air filter and fresh gas with no change in the problem. I was optimistic as I discovered the old spark plugs were for the non super charged engine (NGK BKR5EP-11 and have probably been used for the last 30K miles) and the ignition rotor and cap looked a little rough. I did not replace the spark plug cables as they have less than 20k miles on them. Maybe I should?

One observation is that it appeared to run ok if not fine up until the point the engine was warmed up. It started to miss and hesitate again just at about the time the engine temp allowed the transmission to shift into over drive.

Check engine light is on but this previa has an OBDII port near the fuses but also has the diagnostic port? under the seat. I don't think it is OBDII compliant because the sticker under the hood did not mention it. I tried to pull the codes by jumpering the TE1 and E1 terminals but the only thing that happened is the oil light would blink every 6 seconds (transmission in neutral and key in the on position). I have a OBDII scanner that will be here Sat so will try to read from the OBDII port just to try it. My gut tells me that this problem is sensor related or spark plug cables maybe but my gut feelings are wrong alot lately!

ANyway, if anyone has any idea what I should be looking at please let me know. I have to determine if this can be fixed on the cheap or not. If I can repair this problem, my next task is to rebuild the SAD shaft and replace all four struts/shocks but can't go forward until this problem is firgured out first. If I can bring my previa back to life I'm hoping to keep her for a few more years as it has always been a very solid and strong running vehicle. Well, I also love her too.:thmbup:

timsrv
04-08-2016, 01:17 AM
My guess would be an ECU temperature sensor, but I would want to confirm that with a diagnostic code before replacing. The newest Previa I have owned was a 93, and that one was not OBDII. I'm a little fuzzy on what year that started, but pretty confident it was somewhere between 94 - 96. If you're planning on keeping this long term, it would be money well spent to get a factory service manual. They come up on eBay fairly regularly for under $50. The Toyota manual is way, way better than a Haynes or a Chilton. It will give you detailed information on how to extract codes (among many other things).

Right now the cheapest on on eBay is $56: http://www.ebay.com/itm/1994-Toyota-Previa-Van-Factory-Shop-Service-Repair-Manual-LE-DX-AWD-2-4L-/252194195996?hash=item3ab7f20a1c:g:uysAAOSwnipWXZf n&vxp=mtr Might be worth another $8 to go for this one: http://www.ebay.com/itm/1994-Toyota-Previa-Shop-Service-Repair-Manual-Set-Electrical-Wiring-Diagram-/252086023864?hash=item3ab17f76b8:g:24AAAOSw4SlV8C~ n&vxp=mtr

GreenRiverBoy
04-08-2016, 02:27 PM
I do have a toyota service manual for a 91 but it doesn't cover the sc or any other differences. I think that the 94 manual has a supplement that I would need so may look for a 95 service manual.

Later this evening, I'm going to clean the MAF sensor and also replaced the engine coolant temperature sensor as I have a good one laying around somewhere.

Anyway, thanks for the help. I'll let you guys know my progress going forward.

timsrv
04-08-2016, 02:39 PM
If you're Previa is a 94, then you need a 94 service manual (if you want it to give you accurate year specific info). There were lots of changes from 91 - 94. That 2nd eBay link I gave included the supplement.

GreenRiverBoy
04-09-2016, 03:51 PM
Hey Tim,
I did order that set of manuals with the electrical schematics book by the way. Thx for the links.

So an update on the 94. As I mentioned before, the previa is running fine when cold; that is not the case now as when it is started cold it is missing or cutting out immediately.

I received my Autel AL519 scanner today and first tested it on my 2016 GMC Terrain and a 05 Nissan Sentra. Scanner works fine on these two. So I plugged it into the previa via the OBDII and it immediatly powered on and did a search for whatever protocol the previa uses. It gave me a message that it could not connect. Super bummed so went inside to regroup; came back out 15 min later to try again; it worked! I was able to pull 4 codes three of which I think I created when troubleshooting. Of the four codes the most promising I think is the P0301 (cylinder #1 misfire).

The other codes are P0100 (mass air flow), P0110 (intake air temperature) and P0115 (engine coolant temp). All of these I unplugged while the engine was running.

At this point I'm going to replace this set of cables; my records show that they have 30k miles on them.

Also, I have attached a picture of what looks like goofy oxygen sensor and timing issues and I'm wondering if they are related to the misfiring that I'm experiencing or if they may need to be replaced/adjusted if/when I get the other issues resolved. Is the timing supposed to be around 5 degrees on the Previa?

timsrv
04-09-2016, 04:12 PM
I lack experience on OBDII so anything I say is just speculation. I'm going to assume that you are reading timing advance (which looks about normal). I would suggest putting the jumper between TE1 & E1 with the OBDII code reader installed and see if it changes. If it does, then that should be what your base timing is. Many of the newer rigs (and I think yours fits in this category) don't have the old-school timing adjustment. Other than making sure the distributor is on the right tooth, there's nothing you can do (ECU controls timing).

It's been a long time since I worked as an auto mechanic (back before the days of OBDII). I just got my 1st OBDII compliant vehicle less than a year ago (98 Chevy Tracker) but haven't done any work to it yet. I did just buy my 1st OBDII scanner, but it's still in the package :dizzy:. Hopefully somebody here with more knowledge will chime in to help. I'm guessing your 94 service manual will help immensely. Tim

wades7
04-09-2016, 08:28 PM
reset the computer and see what codes you get, it may take a few trips. Are you sure the maf sensor is working at all? check also at yahoo groups - Toyota Previa Owners. ask on there and search the archives.

Kurtanius21
04-10-2016, 02:15 PM
What about O2 sensors? When those things go bad, your fuel delivery is all messed up, since they control idle fuel delivery and such. I wonder if your obd2 scanner to check for O2 live data. I doubt it's an ignition issue, since your plugs looked ok. Your MAF could be bad, but I generally expect O2 sensors to go bad before MAF does...

bernard 95,96
04-11-2016, 08:06 AM
i would check for a bad plug wire or dist. cap (only use oem toyota cap since it is fairly exposed). the supercharged previa distributor bolts have no slot timing adjustment capability meaning you cant rotate it to change the timing. a common site for dry rot split hose that will throw a code and give rough idle is no. 1 air inlet duct at the sc bypass valve, fig 26, 3-14 chiltons, or check out 2carpros.com, previa o2 sensor not reading

GreenRiverBoy
04-12-2016, 05:42 PM
Thanks for all the input. The end result was a bad #1 spark plug cable. Had ordered a set of NGK's off of amazon and just put them on. Idle is now smooth again.

Thanks again for all the help; now its on to replacing the the struts and shocks and soon rebuilding the SAD shaft.:)>: