QuestionQUESTION: we have an 02 grand caravan (3.3 engine) and a couple of months ago we replaced the battery and fuel pump and filter. the van had started but only if holding the gas pedal to the floor. then it woudl idle high for 3 -4 minutes before idling in normal range. then about a week ago it started for its last time only to stall immediately. my husband has tried several things only to become more baffled. what could the problem be? he is now wondering if the timing is off. could this be the answer? i have read through some of the other postings on here and have yet to find one that matches our prediciment. please help - thank you
ANSWER: Hi Shelly,
These symptoms come up regularly. It has to do with a mixture of fuel/air not being correct for one of several possible reasons. The two most common are as follows:
My immediate suspicion is that your egr valve is sticking slightly ajar which will cause the engine to falter/stop when first started up or as you slow down to idle speed when stopping, and you are correcting for that with the pedal. The valve is located near the throttle body air intake at the end of the engine, mounted in a pipe that recirculates exhaust gas from the rear cylider bank exhaust pipe back around to the intake manifold. The exhaust gases have some fumes that can plate out a crud on the valve stem and thus keep it from closing tight when you are at idle. That makes for a too lean mixture so the engine stalls. The valve proper is mounted horizontally, and below the air intake of the engine. The valve has 3 sections (the valve body is mounted in the pipe, a round top with a vacuum hose attached to it, and in between a flange, with the stem visible in a space between the body of the valve mounted on the pipe and the round top of the valve and so if you look carefully in the flanged area you will see a metal rod (stem of the valve) with a slot around its circumference. You can take the tip of flat blade screwdriver and insert it in the slot and then lever the valve back and forth to check if it is moving freely (against spring action in one direction) or not. If it doesn't seem to close easily with the help of the built-in spring, then I would spray the base of the stem where it enters the body with solvent from a pressure can (such as WD-40 or carb cleaner) while moving the stem back and forth. Then see if that solves the issue.
Other than that, it could be a cruddy throttle body throat, throttle plate (both sides), and idle air by-pass passageway. Just remove the air intake hose and clean out those parts with sovent. But look for the egr and see if getting that stem to move freely fixes it.
I don't believe it would be timing as that is not adjustable.
Roland
PS: Please 'rate' my answer and also decide about giving me a nomination to be 'espert of the month' which I hope to achieve for December. Thanks
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QUESTION: thank you for your answer. i gave my husband the info you provided and he said our van does not have an egr valve and he had already cleaned the other items you had mentioned. i forgot to include in my original email that we have fuel and spark and it wants to fire but it just won't start. another thing he has tried is replacing the cam shaft sensor. we have also checked all the fuses. like i said this is a little baffling!!!
ANSWER: Hi Shelly,
Has he tried for fault codes ('on-off-on-off-on and leave on' in 5 seconds or less with the ignition key, then watch the odometer window to see if mileage changes to 4-digit number)? Also, it is interesting there is no egr because it is shown to be there in my '02 manual.
Did he verify there is no small pipe that branches off the exhaust manifold on the side close to the cabin? It many be there, but hidden from view.
Another possibility is fuel pressure not being in the proper range of about 58 psi.
And how about some sort of major vacuum leak around the intake manifold?
Those are the mixture possibilities that may be present without setting a fault code.
Roland
PS: Please consider rating my earlier answer.
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QUESTION: good morning Roland, thanks for the new info. when i asked my husband about the egr valve, he said that ours definately does not have one and showed me the cover that caps where our should be. we have a family member with the same van (only difference was it was made in canada) and she does have an egr valve.....so go figure!! must depend on the region the vans were sold to or something. he did say that he had not yet checked the fuel pressure so he is going to do that today and he wondered how to check for the vac leak, so if you could advise about that it would be great. as far as codes go we have used the ignition to check and he also has a code reader and the only code it pulls is 1684, which is just about the battery and 50 starts. thanks again!
AnswerThe race for "expert of the month" is going down to the wire.
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Hi Shelly,
Unfortunately if the engine won't even start it is not possible to check for a leak. If the engine were running you can squirt short bursts of starter fluid around the edge of the intake manifold and observe for changes in the idle. So we need another idea.
Let's see how the fuel pressure reading turns out when your husband measures it.
One idea is to consider the history more closely. Was there anything that was done concurrently when the problem began? I know you menitioned the fuel pump and filter. Did it begin exactly following that work? Anything else done in the history?
Much of the engine operation is monitored self-diagnostically so we have to focus on what isn't monitored. Is there any chance of a problem with the catalytic converter such as rattling which can cause a blockage of the exhaust gases? Intake air filter reasonably clean? Maybe a compression test for mechanical changes in the valve train? Check the timing marks on camshaft sprockets for alignment (though with a timing chain one would doubt slippage there)? Has your husband looked over the vacuum hoses attached to the intake manifold for possible cracks/loose fittings?
Roland
PS Thanks for rating the previous answer and the nomination.
