Wrong Spark Plugs in an '88 Sprinter? (JDM Model)

[TZ2590]

Hey Guys.

I recently acquired a 1988 Toyota Sprinter SE Saloon with 150,043km on the odo (yes, 150,043km on a 21 year old car!)

All seems well except for a distinct lack of power under load.

Thought i'd try a couple of cheap fixes first; ran a bottle of Wynn's Spitfire Injector Cleaner through the fuel system (recommended by a friend). This solved half of the problem. Then switched from 91 RON petrol to 95 RON - again, this helped somewhat but the basic problem remains.

Going uphill alongside cliffs, the echo sounds like the engine's pinking...or maybe missing a beat...so I:

• Checked the air filter - near new and thus spotless.

• Checked the spark plugs...again looked near new. As a precaution I cross-checked them against the ones recommended for my particular model and engine (5A-F; somewhat unusual as most Sprinters seem to be 5A-FE) and found that the ones in there are not the recommended model.

Spark plugs currently in there are NGK BCPR5ES
Recommended plugs are NGK BCP5ES

Both models are near identical except the recommended plugs have a .8mm gap (as opposed to .9mm) and are non-resistor (as opposed to resistor) which (finally) brings me to my question; would these subtle differences be enough to upset the electical system when under load?

Read lots of reports of things going wrong when non-resistor plugs are put in an engine designed for resistor, but nothing about the other way round...

Any & All thoughts appreciated

[ae924d]

8 and 9mm?

last time i did mine, and i understand numbers are different between you and i but it was .32 thousands. 8mm is a huge gap for spark plugs..

[TZ2590]

Originally Posted by ae924d

8 and 9mm?

last time i did mine, and i understand numbers are different between you and i but it was .32 thousands. 8mm is a huge gap for spark plugs..

Hell that was quick! Ah, well spotted...figures updated Official NGK pages for your reference:
http://www.ngk.com/more_info.asp?AAIA=&pid=3601
http://www.ngk.com/more_info.asp?AAIA=&pid=3043

[ae924d]

yea, it's a .032" gap for the corolla/sprinter motor .08mm not 8.0mm

what i would do is go ahead and change the plugs to what they are supposed to be and see if that helps, if not to be quite honest i don't know..

[TZ2590]

Originally Posted by ae924d

yea, it's a .032" gap for the corolla/sprinter motor .08mm not 8.0mm

We're never gonna get this figure right are we?!

0.1mm difference doesn't sound like cause for alarm, but then again proportionately 0.9mm is a full 12.5% larger than the recommended 0.8mm...

[TZ2590]

Could someone please enlighten me as to how the function of a resistor plug differs from a non-resistor plug? From what I understand, the resistor prevents the plug from prematurely firing when the charge build-up is not sufficient to properly do its job...or something along those lines. I know that as a result radio and electronics interference drops considerably.

I can just imagine walking into an auto-parts shop and being up-sold to a set of resistor plugs with the promise that my engine will run smoother and, as a bonus, my radio will stop whining. Perhaps thats where the problem originated

My thought is perhaps (under load) the resistor doesn't always build up enough charge every once in a while...thoughts?

[ae924d]

i don't have any ideas on that, i've never heard of resistor .vs non-resistor like i said, just go with what the factory reccomended plug type is, and of course, stay loyal to NGK

[Flashmn]

Actually you're mistaken... BCP5ES and BCPR5ES have the same gap, 0.8mm, the latter has a resistor that the former doesnt, which can cause radio interference and shouldnt be used in ignition systems that dont have contact points.

and what you're describing is a condensator a resistor doesnt build up a charge.