Hesitation

[lukes60]

Had a bit of problem today (well two but one was my dads fault ) I went to a car show, after about 30 mile driving the car it started to hesitate when accelerating moderate to hard, to such a point it was nearly un-driveable on hill and twisty roads , it did the same coming home, same amount of distance, only difference was this time it backfired slightly. Both times turned it off for a few minutes and after that it went on as normal. Ive been told its a common problem by another piazza owner but he couldn't remember exactly what.

Does anyone know what it could be, and how it could be fixed?

We took the distributer off, it does need changing, but gave the rotor and contacts a clean, trouble is, its a big test drive to check if it fixed!



The other problem is my dad sheered a bot in the alternator belt tensioner, that's to be sorted next weekend lol.

Thanks

Luke

[Piazza_man]

Hi Luke, sounds like an electrical gremlin like a faulty sensor or leads. Might be time to change the leads first in case it's arcing. Check the condition of the plugs too while you have the plugs off.

[IZU069]

IMO 90-95% of electrical problems are "simply" solved by disconnecting and reconnecting relevant connectors.
That includes ROTATING fuses (same sized of course!).
[I used to merely remove & check and replace but rotating a faulty or intermittent fuse makes the cause more obvious - even if the fuse fault wasn't obvious - mere multimeter or load testing isn't conclusive!).]

Check battery connections - especially the fuselinks. Their bad connection caused massive angst to a mate - not so much the initial rough running, but the dikhed mechanic that replaced working fuel pumps; blew the ECU, & had no fix after a few weeks.
TIP - take modern vehicles to electricians before taking them to mechanics - unless of course the mechanic is electrically conversant.

Clean battery terminals and the main grounds to chassis etc.

Remember - whenever working on (live) +12V, the -ve/chassis must be disconnected. IE disconnect chassis/ground first and reconnect last.

[lukes60]

Thanks for the help, im thinking the slack alternator belt was preventing enough power to create a spark, so changing the belts, distributor, leads and plugs this weekend.

[IZU069]

I'd say not, but if it was I'd be checking battery etc. Get a DMM if you haven't already got one.

Alternator belts can be quite slack and still operate fine (as I find out when my brackets broke - albethat on a different Isuzu with less electronics).
Belt slippage almost always involves belt squeal. The warning for loose belts is squealing on startup, or when turning on headlights, and sometime brake lights.

But low voltage is easy to test for - a voltmeter or DMM. Though the Piazza has a voltmeter it has insufficient resolution, plus it doesn't measure the batter voltage. I usually mount a 3-digit voltmeter in the dash of my non-Piazza vehicles and they are connected directly across the battery terminals and use a IGN +12V relay to switch its +12V feed but using the +12V output from the main IGN relay should also be acceptable (because its voltage should be close to battery terminal voltage unlike pre-EFI non-relayed IGN+12V could be a volt or 2 down from battery +12V).

Bottom line is that whilst charging, the battery should have ~14.2V - 14.4V across its terminals. 13.8V used to be specified for 12V vehicles but that's history - modern batteries require >13.8V but no more than 14.4V "maximum long-term". Most alternators regulate to 14.2-14.4V.

A fully charged healthy battery should be ~12.7V. That's across its terminals with no load AND after resting after a charge - ie, surface charge has dissipated which may take 24 hours, or minutes if assisted with headlights etc.

Below say 12.6V means the batter is not fully charged or is discharging or faulty.

With the alternator charging, above 12.7V (excluding surface charge) means the battery isn't discharging.
Under high load or low RPM voltage dips/sags below setpoint (14.4V etc) may be normal - it depends on the alternator etc. (My non-Piazza alternator held 14.2V whilst idling at 600RPM just after starting with 500W of lighting.)

When alternator brushes reach their wear-limit its output will drop. This should become evident by its decreasing voltage - especially at higher loads. (When the required demand current cannot be maintained, alternator and system voltage drops. Hence why voltage is the best method for determining system health and performance.)


Long term undercharging of a battery will kill it.
The longer a battery remains discharged, the quicker it will die.
The deeper a battery discharges, the quicker it will die.
When not fully charged, a lead-acid battery forms sulphates which remain soft for a week and harden thereafter.
Voltages higher than 13.8V are required to reverse sulphation.
Above 14.4V causes unacceptable levels of gassing. (That's ok for battery maintenance procedures, but not for normal operation, and it's usually disastrous for sealed aka AGM batteries. Some systems will exceed 14.4V short term after cranking.)


Apols for the ramble. Must've been a long time since I did a battery blurb.

[IZU069]

PS - no harm in preventatively replacing things. Well, usually not. (There is the adage "if it ain't broke..." but that is selective!)
I would always replace ignition parts (points & condensor (not that the Piazza has them!), rotor & cap; splugs; maybe leads) and belts - and usually cooling system rubbers (radiator & heater hoses) & thermostat - whenever I got a "new" vehicle on the road. Oh - and oil and filter and air and fuel filters. (I'd usually also overhaul the brake system but that was mainly for single circuit and drum systems.)

In later years I learned to get the radiator professionally flushed and checked - ESPECIALLY after any engine rebuiild etc.

Any replaced sparts that are ok can be used as (emergency) spares.
But having such sparts replaced meant (in theory) that they would not cause problems - whether continue any existing problem or create new problems as hoses leaked or burst etc.

It was often my standard stipulation if anyone came to me with operational problems and no maintenance history... well, the ignition stuff at least, and filters.

[lukes60]

Hi, thanks for the help

I got the belts changed this weekend, the alternator belt was very slack, nearly coming off. The previous owner had fitted belts that where slightly too long. Im going to order plugs, leads, distributor from IPTOC, so should hopefully get it all sorted . Its got full comprehensive service history up to 2012 (always serviced by the same bloke since 93), since 2012 it did 300 mile, so I still think its best to get a few things changed.

Thanks

Luke