P0171 and P0174, and then P0300 2000 Isuzu Rodeo

2 days ago I had P0171 and P0174 and the truck's idle was off with hesitation on acceleration response. I inspected the ducting from air filter and cleaned the MAF with contact cleaner. Cleared the codes and drove it for another day, codes did not come back, but engine was still not right. Today I got a P0300 and engines seems worse, with more hesitation on acceleration response. P0300 flashed on and off as I drove back home.

It has 122,000 km (75,000 miles) on it.

Any suggestions?

Thanks!

how's it run with the MAF disconnectted? it sounds like the fuel pressure is incorrect or an egr sticking maybe! assuming the MAF is okay. How old are the spark plugs, ignition pieces etc?

I can go try it with the MAF disconnected.

Spark plugs are original, book says to replace every 160K kms. Other ignition parts would be original as well.

I cleaned the EGR about 3 months ago, sprayed it with cleaner. Fuel filter was also changed about 3 months ago.

This morning I put in a bit of fuel injector cleaner in a full tank, but it was running rough for the last few days.

I will run it without MAF connected, see how it runs.

Thanks for the help.

I went around the block with the MAF connected and then disconnected. I could not really tell the difference. Both cases seemed a lot better then earlier today, so it is kind of intermittent or maybe it happens more when the engine is warmed up.

I guess that I will just clear the codes and run it. If it happens again I will take it to a pro.

Thanks

Yeah ignore what the manual syas about plugs lasting that long! they never do and if they should the chances of removing them from the cylinder heads without breakage are slim to none, I'd replace the spark plugs, wires, dist cap rotor etc if it's equipped with one, a fuel filter if it's never been changed etc. Replacing a MAF or anything else at this point would be pointless until the basics are covered.

Good luck and keep us postted

Jeff

I replaced the spark plugs with ACP05. I was not able to find any of the 3 listed in the manual, but these are listed as a replacement on a few sites and from local parts store. Afterwards I read that these trucks are a little picky on plugs, so not sure if they will cause issues.

I took it for a drive and at first it seemed ok. Higher speeds were fine, but when I slowed down in town it started doing the same things as before. I then got codes P0171 and P0172.

I think that I will have to take it in to get full diagnostics done, I have gotten a lot of different codes...

Any ideas?

I am still having issues with this.

I took it in to dealer and they replaced the intake manifold gasket (there was an obvious leak, found by spraying carb cleaner around gasket), changed the oil and checked the plugs that I installed. The misfires and idle was greatly improved, but not 100%. They suggested that the plugs should be replaced with Denso PK16PR11, which are recommended for my engine.

I replaced the plugs with the Denso PK16PR11, gapped to 1.05mm (I did a quick search and they are the recommended plugs). I also replaced the PCV valve. No real change, no codes, but still has misfire and idle issues at low speeds.

Next, I removed the EGR valve, the gasket did not look that good and there was some dirt under it. I cleaned everything and replaced the gasket. No real change, no codes, but still has misfire and idle issues at low speeds.

Any other suggestions before I take it back to dealership and get raped?

Thanks

aaa

Yeah I think Im getting too busy "raping" customers to be of much help!

I edited my post, so as not to offend.

Jeff, I am not implying that all dealerships or mechanics rape people. But, the Isuzu dealership that I purchased the truck from and am basically forced to get service at does. They wanted $24 per plug, not installed, I bought the same plugs for $7 each. I bought the EGR gasket for $2, they wanted $17. They deserve to be paid for there knowledge and labor, but the markup on parts is crazy.

Thanks

aaa

I stated that mechanics should be compensated for there knowledge and labor, I have no issues with this at all. I have issues with excessive markup from the dealership on parts. I fully understand markup and the need for companies to make money to stay in business. I bought the plugs and gasket 3 blocks away from the dealership, so how can the dealership justify the extra cost? If they are required to have those kinds of markups to stay in business, then something is wrong with their business/industry. The place that I bought them from also has markup. I don't think that I should have to just blindly except what the dealer changes for the same parts. The labor charges are standard ($105 per hour) and known upfront, but once they find the problem and have it all apart, they can charge whatever they want for the parts.

They are double platinum plugs and were recommended in the manual and by the dealership.

I will most likely just take it back to the dealership, due to the same reasons that you bring up.

Thanks

price markup at dealers often has to do with increase warranty period on some parts versus the chain stores and suppliers! in addition increased overhead at dealers means it has to be picked up by all depts within the dealer , not just parts, sales etc! My preference with dealer parts stems from the fact that if parts are revised and improved to prevent future problems, Ie revised intake gaskets on GMs then most of the time the dealer has access to them before the chain stores! plus I almost always get the righ part the first time unless I don't give them the vin#

aaa.