My car has had rough idle and sometime stall. The problem is; it is a very intermittent issue and whenever I brought it to my mechanic, the problem wouldn’t be present. I had the engine light on so we hooked up the diagnostic tool. There were a whole bunch of codes that showed up and everything pointed to fuel related issues. My mechanic told me that the problem is not very obvious and to make things worse, the intermittent nature of the issue makes diagnosis even more difficult. There are a couple of possibilities and he suggested we start by replacing the least expensive parts and see what happens.
By now we replaced the throttle body (it was my suggestion), the air mass flow sensor, the fuel pressure sensor, the fuel pump module and the fuel filter but I still have the same issue.
My question is; is it reasonable at this point to expect that he all future repairs related to this problem be free of charge? I do see his point and I am not sure what else I would do in his place but on the other hand I am getting frustrated and frankly, I feel like I am paying for nothing.
What would be a reasonable expectation on my part towards the garage?
You certainly owe for the sensor you wanted replaced and it seems that you agreed to the other work. I agree with @VOLVO_V70 in that you need to find another shop if you are dissatisfied with your current mechanic’s work to date. Tell us what car you have, the mileage, and post all the codes you saw with the scanner. Maybe we can help you figure it out, but we need that information to do so.
Absolutely NOT.
He offered to try changing parts because he was unable to nail down a solution and you agreed. You owe him for his expertise, his shop time, and the parts.
Year make and model?
Miles on the car?
Maintenance history (to the extent you know it?
What were the codes?
Did the mechanic check the compression? What were the readings?
Based on your description, I’m going to guess that this is a tired old engine with multiple problems. Sometimes an engine collects so many accumulated wear issues that it simply can’t be repaired without a major rebuild. Mechanics will sometimes struggle to try to get it running better. I commend your guy for offering you the option to let him try replacing parts in the hopes that something helps. I know of a dealership that just changes the ECU for $X,xxx dollars if they can’t verify a cause. He sounds like an honest guy trying to help you with an old engine.
Point well made, db, but sometimes people would rather gamble a few hundred or so in the hopes that they can avoid getting a new motor. It’s tough for someone on a tight budget to accept that their engine is shot. And, unfortunately, there are a great many hard working and honest people living paycheck-to-paycheck, and for a huge variety of reasons.
I’m curious… did he perform and diagnostic tests besides the code reading? Like perhaps a compression test? Are the results written on your copy of the shop order?
I basically agree with Nevada’s first comment, but based on your original post it sounds to me like he told you the engine was worn out, discussed it with you, and you asked him to try changing some parts at your expense anyway. I’d be comfortable with his doing that if that’s what transpired. IMHO it’s better than sending you to someone that would use it as an opportunity for enrichment without being honest wth you.
Intermittent problems like this always create a difficulty for the customer. This is a common thing reported here. The shop will be happy to use the try this, try that approach, using their best educated guesses. But as you’ve discovered it’s very easy to run out of money before running out of guesses.
And no, the shop won’t and shouldn’t be expected to keep up the guess method repair schedule for free. You’ll have to continue to pay for parts and labor as before. They haven’t issued any written guarantees, right? I don’t think so. It’s like if you are ill, the doctor doesn’t guarantee they’ll cure you for a fixed fee. The doctor’s only guarantee is that they’ll continue to keep treating you, trying their best to cure your illness, indefinitely, charging their normal fee for each visit, until you are satisfied with the result. Same w/auto shops. That’s the most you can expect.
The best solution to this problem imo is to give your car to the shop to keep temporarily, and ask that one of their techs uses it as their daily driver. Eventually it will stall with the tech driving, and then the tech will more likely be able to figure out what’s happening on the spot. In the meantime, you rent a car or otherwise find your own transportation. Overall I think this is the most frugal solution for you.
As far as technical idea to consider, things that can commonly cause intermittent rough idles are
faulty egr valve
faulty ignition module, power supply to it, or crank position sensor
faulty fuel pump, or power supply to fuel pump
Shops can install fuel pressure gauges, volt meters monitoring the ignition module and fuel pump power supply , etc which the owner can watch while driving, and tell the shop what those do when the symptom occurs. So that’s another idea. Best of luck.