toyota_mdt_tech

Yes, a code 71, no EGR. Did someone swap some vacuum hoses around? There will be 3 small metal pipes arranged in a triangle about #3 spark plug area. The vacuum hoses going to them shall be marked. Tope one must be #3, bottom one on the rear is #5, bottom right is #6. There is a little air suction, that will have #4 vacuum hose going to it. Others goes to the gas filter (which isnt a fuel filter) and that is basically a vacuum tree on the intake (vacuum port wiht a filter in it) and those will be marked #0. If you already replaced the modulator, I'd get a vacuum pump and try to open the EGR valve. Or run the engine and rob a vacuum source and hook it to the ERG and see if the engine stalls or almost. Technically, at idle, it should stall. Now one way to eliminate the light would be to unplug the EGR gas temperature sensor and short the wires together. But EGR is nice to have, it does help reduce ping. A 1991 with the EGR temp sensor, you must have a California model emissions, right? Oh. fo by fo, sent you a PM, thansk for the kind workds on my 2004 Cargomate too! An EGR valve is spendy, and prety easy to replace. Holler if you need more help.

callmej75

4 small bolts on the plenum, 2 large nuts holding the pipes onto it. Disconnect the vacuum lines. Not much to it. I would think if your egr valve was going out, then you may be running crappy?

callmej75

Some have temp senders and some don't...could be the temp sender even? If i remember....that is a different code....don't mark me on that. I kicked at this problem for 4 months one time. It aggravated me to death!

toyota_mdt_tech

Code 71 is insufficeint EGR flow. It wont show excessive like an OBDII rig will. EGR gas temp sensor is onyl on the Cally models, up till about 93, then thye all got it. Cally or not. The sensor isnt bad, it looks for "heat" when its supposed to be on. The sensor is how it sees heat or not. A good way to see if its working while setting in the driveway is to spray some WD40 on the flexible pipe under the valve. Then hold the throttle about 2000 rpms, and about 2 minutes after starting it, you will see it open as the pipe will start to rapidly burn off the WD40 (emits some light smoke). I can get the manual specifics on testing the EGR system if you want to PM fo by fo. I also might add, I mentioned shorting the EGR gas temp sensor pins, this doesnt fix your problem (inop EGR) it just makes the engine ECU ignore the EGR system. In fact, non cally models had a factory short pin plugged onto the ERG gas temp sensor wire. So it will never set that code again.

callmej75

Some good info there! Did not know they had the temp senders on all after 93...my bad!

Fo by Fo

Cool, thanks for all the info guys. I'll definatly try to check it this weekend when I have some time, and my truck hasn't been running funny. Runs normal just has that little pesky light, I'll try that WD40 trick you mentioned

ReneB64

Toyota MDT Tech....maybe you have some advice for me....
I have a 1993 toyota 4x4 3vz pu; had the head gasket replaced, a little while later, about a month, I come up with CEL - code 14 and 71. Took it back, they say they checked the EGR valve and its ok, and supposedly so it the ignition system; they say it is the Temp sensor, but I have read that usually isnt the problem, what do you think?

rdharper

When I first bought my '94 (in May of this year) I got a code 71. Cleared it, came back on in a few miles. As I needed to register it, and therefore needed to pass the smog II requirements in California, I took it to the dealer. They charged me $75 bucks for the diagostic work, told me somebody had reversed two of the 3 EGR lines. Truck ran fine after that, and passed Smog with no problems. Just thought I'd pass that on.

That dealership, here in San Jose, has been inexpensive, quick and fair, based on the few times I've taken anything in to them. Of course I'm asssuming what the dealer told me was correct, but I have no reason to doubt them as they could have charged me for parts which would have run up the bill. So I believe them. For what it is worth there is a second dealer in San Jose, which has been expensive, but also does a good job.

Guess my point is that sometimes a very simple fix does it. I would have spent a ton of time and money finding that problem if I'd of shotgunned it.

toyota_mdt_tech

Code 14 can make you a pedestrian. Its basically a communication problem beteen the ECU and igniter. There is 2 wires, IGT and IGF, (trigger and fire) and there is no communication. Open, shorted? Can also be a bad ECU or igniter, but open wires is the most likely problem. Code 71 wont make you a pedestrian, not enough EGR. Hooked up wrong, modulator, valve itself, plugged EGR passage? It almost has to be one of those.

Fo by Fo

Thats interesting that you mention it came on after you had your head gasket replaced, mine came on after my head gasket was replaced too. It first came on in August I believe, but I've just been too busy to really fix it. (Its amazing how time flies, huh?) And here we are in December. Anyways I tried that trick with the WD40 on the egr and nothing started smoking so I sprayed some more on there just to make sure I had it nice and oiled but I think the only thing that was smoking was the stuff that dripped down onto the exhaust manifold. So which hoses are the ones most likely to get swapped? Sounds like that just may be it as the check engine light didn't come on before the head gasket.

ReneB64

Thanks for the feedback; is there a chance the 14 and 71 are related? They both showed up at the same time, and when I reset the ecu, they both show up together.

I found a couple of vaccum hoses that were related to the EGR system off their valve (vgv?) I dont recall the name of the valve, but I may have inadvertantly knocked them off when looking around. Then again, maybe they forgot to connect them when they did the heads. we will see in the next week if the CEL comes back. Just seems wierd that athe 14 showed up with the 71. I checked the connections, wires, cleaned them... not sure what else to check.