QuestionTed, I did pull the cold start injector and tested it. It sprayed fuel and shut off and appeared not to leak as the engine ran for a few minutes. In this process of elimination I'm down to the EGR valve or an injector stuck open.
1. Are you sure that a malfunctioning EGR valve could possibly not trigger a check engine light? I thought for sure that it would register a "hard code" to the OBD(remember no check engine light is showing).
2. Would isolating the EGR by disconnecting vacuum hoses show anything?
3.To see if an injector is malfunctioning would removing a spark plug wire, one at a time and listen to engine performance prove anything as far as an open injector would be concerned? I have not tried using the "stethoscope" method yet but I will.
thanks again for helping me. John
I feel like I'm getting closer to why this auto is getting 15mpg and idling so rough.
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Ted, Why not a fuel injector cleaning service?
I did check the resistance of the injector and it's within specs. But I have not yet tested it via your direction. Still don't know how I'm going to plug the hole while I'm testing the injector. Any ideas? Also when I find a vacuum pump how do I test the EGR? Is it simply taking off the hose at the nipple, plugging that hose, hooking the pump to the nipple and putting vacuum to it? then if the engine stumbles the EGR is working?
Thx, John
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Ted, How can I check the cold start injector leaking? If I disconnect the electrical would that prove or show anything? Also, is there a way to test the EGR valve without a gauge and is that valve hard to replace yourself, can you clean it? Both items are expensive, would you install used ones if you could find them?
your the best, John
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Hi Ted, I have 90 Celica (2.2) with 75k. I just bought it $3,000, one owner. It really runs rich, idles rough(geting 15mpg). It hesitates(bunny hops) around 20 mph and then seems to pan out. Has great power when I step on it. I thought 16 yr old? change plugs (Denzo), wires, cap,rotor, coil(all was still original). Also O2 sensor,air filter, thermostat,vacumm modulator(small filter was filthy)cleaned throttle body,check TPS to specs. I have tried to adjust idle screw but no change. I really don't know how to check EGR valve(no vacumm gauge, CAN YOU CLEAN IT?) I thought maybe cat converter( big$) but I'm running out of backyard mech ideas. I took it to Toy dealer and they said nothing wrong, no check engine light, waste $80. I'm think an injector is stuck open, I wouldn't know. Would a fuel injector cleaning be worth a try, another $80 I would do it.? Would a compression check reveal anything? Thanks for helping us amatuers
MERRY CHRISTMAS, John
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Fuel injector cleaning probably won't help at all, a rich air fuel ratio is also not caused by a clogged cat converter, an injector staying open can cause it, this engine also uses a cold start injector on the intake plenum chamber which could be leaking, the egr valve could also be the cause if it's staying open at idle, if you don't have a vacuum pump to check it I would suggest having someone check the valve or borrow a vacuum pump to test the egr system.
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The cold start injector can still be leaking even with the wire disconnected, you can remove it from the intake chamber and block the opening somehow to prevent a vacuum leak, then start the engine, the injector should only spray fuel while the engine is cranking, EGR valves can't be cleaned on toyotas, yes, I would definetely consider used parts, it may be cheaper to substitute suspected parts than to pay the diagnostic fee just to find out what may be wrong and by the way I would not have any confidence in the dealer that told you there was nothing wrong just because there was no check engine light on, on the early OBDI sytems there can be a lot of problems that will not trigger a check engine light.
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Try finding a rubber plug at the hardware store that fits in the opening on the manifold or just use some duct tape, applying vacuum to the egr valve directly should kill the engine at idle but if the egr valve for some reason turns on at idle it will cause a rough idle condition and yes it's possible for one of the injectors to be staying open, with the engine running at idle you can listen to each injector by contacting each one with a long screwdriver held to your ear to hear the clicking noise, the one that doesn't make aclicking noise is the one with the problem.
AnswerOn this model the check engine light will not come on if there is excessive egr gas flow, ie: a stuck open egr valve at idle, the check engine light will only trigger if there is insufficient egr gas flow so it's possible for the egr valve to cause this, keep in mind that egr flow is only supposed to happen at cruising speed and never at idle, the valve should be off in that case. But before replacing the egr valve you can do another test, remove the egr valve from the intake manifold and plug off the hole in the manifold, you can make a block off plate from a piece of thin aluminum or even plastic, this will eliminate egr flow completely from the intake system, there will be some exhaust noise from the open port to the egr valve but you can see if the engine runs normal, removing the samll vacuum hoses doesn't eliminate the egr valve as the cause. If the bad idle condition still exists with the egr valve out of the loop you can exclude it as the cause.
