free hit
counters
Low voltage under full power - Engine/Ancilliaries - The Lotus Forums Jump to content
Sign in to follow this  
Stockcar44

Low voltage under full power

Recommended Posts

Help. Freescan shows voltage drops under full power, dropping as low as 12.3 volts and returns to 13.6 under normal cruise. New Bosch alternator and new battery. Cables good and I even added an extra ground wire. Anyone got a clue as to where the voltage is going or if this is normal?

I'm looking for a reason that causes the car to go from perfect operating conditions at computer reset and progessively gets worse over the next 50 miles, like it learns backwards getting dumber the more you drive it.

Marc in CA

89 SE

Share this post


Link to post
Share on other sites

Upgrade today to remove Google ads and support TLF.

Hi Marc,

My voltage also follows the same changes. Its strange (you would expect it to be easier to hold 13.6v at full engine speed), but I have put it down to the point at which the voltage is measured in the ECU. It would be nice to see what the voltage is at the battery terminals, logged by an independant device (not the ECU).

I am not a freeescan or coding expert, but I do know that when the ECU is reset it will run the engine 'safe' (i.e. a little rich) for a while while learning the new parameters. Idle immidiately after reset tends to be better than idle after the ECU has learned. When I had a stumble problem, it was always better emmidiately after the reset and got progressively worse. My problem was an irritant rather than a major issue. I progressivley worked through all the componants that effect the running qulity, replacing as I went, and things got progresivley better.

It seems that all componants have to be spot on to get near perfect running and idle quality.

I changed (in order of largets effect to smallest)

O2 sensor (biggest improvment)

fuel pump

injectors

fuel presure reg

TPS

plugs

plug leads

coil pack

ECU!

Even if freescan is saying the O2 sensor is working OK, it is worth changing since mine seemed to be working fine but the engine ran much better with a new one (use genuine Lotus part, people hace had problems with non OE O2 sensors in the Esprit).

Good luck

Malc (also 89 SE)

Edited by Malc Holmes

Share this post


Link to post
Share on other sites

maybe the belt to the alternator is slipping at higher engine speeds. Try some belt dressing to stick the belt a little bit more to the pulley.


89 White Esprit SE

...a few little upgrades....

93 RX7.....Silverstone

....slightly modded...Muahaha...

New Addition:

1990 300ZX TT......Hmmm

Share this post


Link to post
Share on other sites

Thanks guys. I have replaced the O2, TPS, plugs, wires, ECU, New belts, New Alt, checked vacuum leaks, IAC new. Maybe it is weak on the fuel delivery, I haven't check that because it pours the fuel in under full throttle and takes off. The secondarys work according to Freescan.

My experience tells me it is a lean condition, just feels like a weak burn under cruise. Another thing that happens is after it gets 50 miles on the reset, it stumbles a bit at the stop sign and then catches itself and burns the tires off at half throttle with no turbo spooling (a few pounds of boost really). That feels like a timing issue. Maybe I have a bad ECU again or the memcal is lost in space.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Sign in to follow this  

×
×
  • Create New...