97 Tacoma 2.7L rough idle and take off

We are having major problems with my husbands 97 Toyota Tacoma 2.7L 5spd.

Here’s what’s going on. At start up it idled high even with the idle screw all the way backed out as if there is a vacuum leak. When we replaced Egr and modulator it idled down but the idle fluctuates about 60-100 rpm. White steam came out of the exhaust 1-2 times but it doesn’t smell like coolant and it had been after we replaced Egr which we put seafoam through about a week before and think that maybe it was just stuck and didn’t get that seafoam out until replaced. It bucks and runs very rough at take off. No matter cold or hot. O2s Stft and Ltft are doing there jobs but aren’t being consistent. No matter what we’ve done the only outcome we have had is as I said the idle wasn’t over 1000 once we replaced Egr but it is still fluctuating. My husband and I are both just at a loss if what to do we are both mechanics. Any suggestions to help before we just give up. We love our truck very much.

Here is what we’ve replaced

Head gasket

Maf sensor. We had problems with the after market ones so we got another Toyota one.

Coil packs (aftermarket duralast)

Spark plugs to ngk iridium and original toyo plugs

Spark plug wires (aftermarket duralast)

Ect sensor (we had a code finally) haven’t had it back (aftermarket duralast)

Egr (aftermarket duralast)

Egr modulator (aftermarket duralast)

Cam sensor (Toyota)

And o2 sensors which I’m pretty sure they were ngk.


No codes have been thrown other than the ect sensor ones and prior to these problems we have maintained the truck and kept it in great condition as it’s my husband’s daily driver and we go on many trips with it.

Prior to all of this we have also replaced fuel pump with an aftermarket one.

Edit: we just found out when we unplug the o2 sensors it runs fairly normal for a bit then does the same thing. I’m thinking it definitely would have to be something with air fuel ratio not being measured correctly.

 

Our Tacoma

 

Smoke test it and eliminate vacuum leaks would be my first step

 

We will we have checked all vacuum lines the only thing we haven’t done is a smoke test. At first it appeared to be a vacuum leak but it no longer does. We will smoke test it and I’ll let you know the results

 

It would help to eliminate leaks from your troubleshooting. Also when my IAC started going bad, my idle was very inconsistent.

 

I totally forgot to add that in. We thought it was the iac we cleaned it and nothing happened so we replaced it as well still nothing.

 

Sounds like you have a good plan. The last iac I put in was bad out of the box. I had a new problem of constant stalling, before it was typically a hanging idle. But this was a parts store special.

 

We are just at a loss. We will smoke test it hopefully the new iac isn’t bad. The worse part is the bucking.

 

I can see why you love it. Very nice specimen

 

I got a dumb question for you.....a 97 uses a distributor.....

so how do you have coil packs.......

Reason I ask.....is the dist models are notorious for getting tiny little shorts in the distributor and being a pia to track down....

Takes a probe and two people ......one to turn....one to probe......


Guess you've done simpleist thing first.....and that is double check and maybe even reset your grounds.....make sure all fresh.....theres even an unshielded shunt or two that go into the ecm....

I've even ran a straight to block ground instead of relying on a body ground......

Sometimes fresh fuses or just reseating them can make a difference......and allows double checking all connections/bolted cables coming in/out of fuse box....
these are getting very old you know.....thermal expansion thing....not to mention dissimilar metals....

 

It doesn’t have a distributor, thank God but grounds are all checked and cleaned with no shorts. It was imported and manufactured in April of 97 but also has a 98 make of the same motor. (2.7 L 3RZ) if that helps. Fuses all are fine and we replaced a relay that was bad (taillights) any other thoughts?

 

Solved: We replaced tps sensor weeks prior to all of this happening from autozone. We have had multiple problems with them now so we went to advanced and got one and now everything is perfect. Went through a lot of parts. All that would’ve needed replaced eventually anyways. Just heads up watch after market parts from autozone. We’re pretty much done with autozone for anyone who doesn’t know like we didn’t old Toyotas are picky and autozone doesn’t always make the cut.

 

Toyota engines really do best on toyota oem engine sensors.....
I'm not that loyal on rest the vehicle......
I know they're expensive.....and half time have to order em.....

Infact the way the MAF connects directly to the ecm......generic one could cause damage.....