Piston Slap: Slip Streamin' a Poor Idle?

piston slap slip streamin a poor idle

TTAC commenter Sjalabais writes:

Hi Sajeev,

I wrote to you once before about choosing a sensible family beater. In the end, I bought a 2002 Honda Stream, which I have since driven 30,000+ km. It’s a very rare car in Norway; only 147 on the road as of this year.

The Honda has been fairly reliable (lots of brake issues), practical enough (try to beat a ’70s Volvo!) and fairly robust. What I like is that it can take a beating when we go to the mountains.

Over the course of the last year, an odd issue has become an annoyance: Sometimes, the car will start, but not hold revs.

Without extra gas, the engine dies. Drive the car for half a minute, and everything’s well. The issue usually rears its head when my wife drives it, or when I’ve been stuck driving very slow in traffic. Driving with low revs is the only possible cause I’ve come up with so far.

Any ideas what I should look for? The engine is well maintained. Plugs and cables are new; oil and air filter are changed regularly. A shop deemed the compressor governor fit for service. Should vacuum hoses be checked?

Sajeev answers:

You just loooove giving me difficult questions, don’t you my friend? Do me a favor: buy a Crown Vic or something LS-swapped for your third query to this column.

The normal maintenance items seem covered. Perhaps the most obvious culprit to a poor idle condition is the idle-air controller. If your D17 engine has a fast idle thermal valve, clean that too. Some IAC units can be cleaned (along with the throttle body, please!) but others must be replaced.

Depending on mileage and level of blow-by, a blocked PCV can cause a poor idle. And maybe the PCV isn’t blocked when you pump up the crankcase pressure via winding the hell outta that motor, unlike your more conservatively driving wife. So you do have a few choices:

  1. Free: Clean IAC, fast idle thermal valve, throttle body.
  2. Cheap: Replace all rotted vacuum lines, discard old PCV for a Honda-branded replacement.
  3. Cheap-ish: Replace IAC.

Is this likely to work? I think so, but the Best and Brightest always have the final say.

[Image: Shutterstock user Mikhail Abramov]

Send your queries to sajeev@thetruthaboutcars.com. Spare no details and ask for a speedy resolution if you’re in a hurry…but be realistic, and use your make/model specific forums instead of TTAC for more timely advice.

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4 of 20 comments
  • Sjalabais Sjalabais on May 17, 2016

    To sum it up, fix ALL THE ISSUES. Last week, I rounded 40k kms in the Stream, and the idle issue persists. It has been like this for a year, and I know it comes off incredibly lazy, but since this issue can be fixed by just starting the engine again, I haven't prioritized hunting for it. Just that little instructional video about the fast idle thermal valve above lists three potential causes for bad idle on one part... On thursday, I'll have to pass the biannual tech inspection. If that hurdle is taken without too much hassle, I will follow your very timely advice (and further comments here) and get to work. Thanks a lot!

    • Ryoku75 Ryoku75 on May 17, 2016

      I thought they did away with the FITV in 96? If thats an issue, it might have been previously tightened too much causing your idle to drop.

  • Ryoku75 Ryoku75 on May 17, 2016

    Seriously? Almost 10 years later and Honda still cant figure out IACs that dont plug up? I've had to do similar work to my own '94 Accord, but its old and such, even with newer pads the brakes arent that great (compared to old Volvos). You'd think Honda could fix these shortcomings by 2002. Despite the age my Accords been decent, easy and cheap to get parts for, however I cant say I'm not a little sour over the AC compressor crapping out on me (despite regular servicing).

    • Sjalabais Sjalabais on May 18, 2016

      My AC compressor appears to have started leaking the other day (I first thought my radiator was on the way out). I'll have that checked tomorrow, but everything's pointing towards foregoing the benefits of AC - just fixing a plug and a refill would set me back 250$ in Norway, the lowest possible cost according to the shop. That would be about 5% of what the car is worth.

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