yotamanmn

My 93 truck is not running right. The is no check engine light on. the problem is that when you start the truck cold it idles rough and runs rich. once the motor is warm the truck will not idle. it also runs rich. Need help thank you.

neilan

do a search. How do you even know it is runnign rich? if it runs rich it could easily be the cold start injector stuck open or the cols start injector switch is busted. or it could be the afm, fuel injectors or pressure regulator.

Darksyde4Runner

My 90 does the same. Also very interested in the fix

Bunta Fujiwara

My '93 did the same thing until I fixed it. The fix is this:

The problem is most likely in your intake, combustion chamber, exhaust or ECU. If it's in the combustion chamber, it'll almost always be connected in some way with the exhaust system as well. That's how mine was.

To fix it, first determine which system the problem is in. Start with your air filter, spark plugs, and exhaust manifold. Begin by examining the air filter. If it's dirty, replace it. (I'd reccommend a high quality example from K&N, myself. It'll last a very long time, and it'll possibly outlast your whole truck, even). Next, examine the spark plugs. If they're corroded or just generally bad, replace those with either Toyota-Denso or NGK factory specified plugs. Titanium or gold plated are the best. They're not too expensive. You can probably get them the easiest from your local Toyota dealer, along with all other parts. Finally, take off the upper part of your exhaust manifold (the portion that bolts directly to the left side of the head) and check it for carbon deposits. If you have them, then your problem is identical to mine. I never had the check engine light ever come on, and a bad air filter and plugs, therefore causing massive carbon deposits from unburnt fuel.

If that's your problem, then great (for the fix, not for the fact that you had it in the first place, of course). Address those three areas, and problem solved.

If not, then it's in the intake/ECU area. Could be overfiring injectors by assuming that it's always cold. Could be a bad AFM, or bad sensor signals, or even a bad TPS.

Your problem could be as easy to fix as replacing an inexpensive sensor, or as medium as the fix for my problem, or even as hard/expensive as replacing a whole ECU.

Hopefully it's not the latter one. The middle only cost about $30 to fix, and you probably already know about price of the former.

Hope that helps. Let me know how it goes by posting in here or shooting me a PM.

yotamanmn

Thank you. I have all ready done plugs, wires, cap and rotor. But if will look in the rest. And i can smell the fuel out the exhaust.

Bunta Fujiwara

I could smell mine too, back then.

4runnerx3

First three things to check, water temp sensor for the ECU, air temp sensor inside air flow meter, O2 sensor.

thook

Bingo...

91TPU

i didnt see it mentioned, but what about your timing...if your running rich, then that should def be something you should check out!

corvettelvr73

So when do I spray carb cleaner into. I'm a little confused.