Sell Your CAR - Place your FREE Autos listing
Advertisement

BACKYARD MECHANIC: Test fuel pressure for 'hitching' problems

Advertisment

2013 Honda CR-V LX for $25,995

2013 Honda CR-V LX

View 126 more Honda CR-V listings.

QUESTION: In 1999 we bought a new Chev Astro van ('98 model). It has the 4.3 Vortec engine. Shortly afterwards it would take spells of 'hitching' while driving at highway speeds. It was more prominent when the engine was not pulling hard, just at the coast point. It would never set a code.

Last summer I changed the plugs, wires, coil, distributor cap and button, hoping to fix the problem, but to no avail. It finally set a code so I took it to a GM dealer. They scanned it (code P0300) and told me that three injectors were not operating within their limits. They replaced these and during the test drive it set the same code again. They checked for an external vacuum leak but could not find any. We had to leave, so I paid the $1,000 with no fix. Can you point me in the right direction for a fix?

ANSWER: The P0300 code that is setting in your van is a code for a general engine misfire. From your description, it sounds like a lean air/fuel mixture misfire. Because the misfire is random, it's more difficult to locate, but there are some things to check. Usually I would start with ignition, but you've replaced that already.

These vehicles used an electric fuel injector connected to a hose that leads to a spring-loaded poppet valve. The poppet valve is where the fuel sprays into the intake port. It was common for these poppet valves to become gummy and the fuel wouldn't spray in a fine mist. This could cause a misfire.

Cleaning these injector poppet valves with conventional injector cleaning methods didn't work well, so GM dealers have a tool that forces nitrogen gas through the poppet valve to free it up. I would try this as my second operation before doing any other repairs.

First thing, I would test the fuel pressure. These systems are very sensitive to low fuel pressure and even a couple of PSI below specs (52-60 PSI) can cause a misfire. A weak fuel pump may be the culprit. That should get your van running fine again.

QUESTION: We have a 2012 Honda CR-V with approximately 9,000 km on it. We had no problems up until mid-September. When my wife came out after shopping, the car would not start. She got a boost and took it for a good run. The next day it worked fine.

The following day it would not start, so I got another boost and took it in to the dealer. They replaced the alternator and trickle-boosted the battery.

On the following day it would not start again. I got another boost, drove it to the dealer again and, after several checks, they said the replacement alternator was bad so they ordered one in. The next week they called and said the replacement alternator was good but the battery was bad. They replaced the battery with a higher-amperage battery and charged it. It's starting OK now.

Originally, the dealer mentioned having the radio on while parked could kill the battery. The question we have is why did it go dead now {after six months} and not before? Would we have this problem at a later date?

Now I notice the driver-side mirror heater is not working. Does this look like we will have continual problems? Hope you can shed some light on this issue.

ANSWER: You could have had a battery with a bad internal connection. This isn't common, but it does happen. The battery problem can be intermittent, sometimes starting the vehicle and sometimes acting like a dead battery. Test equipment often doesn't find this type of problem unless a high load is placed on the battery during the test.

Operating the radio while parked will kill the battery, but it would take a couple of hours or more if everything is in good condition. The mirror heater not working is likely unrelated to the dead battery, but I would get it repaired under warranty. If an electronic module on the vehicle is faulty, it may not operate correctly and may not "go to sleep" when the key is off. This would drain the battery over several hours and can be tested using an ammeter to check for an electrical drain on the battery.

Jim Kerr is an experienced mechanic, instructor of automotive technology, freelance journalist and member of the Automobile Journalists' Association of Canada.

kerr.jim@sasktel.net

Advertisement