My magnetic clutch stops between 2700-2800 rpms and does not coming back on until 2490-2550 rpms. Pump should stop at 3250. Why is it coming on again so late??

In neutral. Engine at operating temps. At idle, A/F ratio's read [15.8 to 17.0]Accelerating to 2500. A/F ratio show lean [around 19.0-20.0] Around 2500 ratio's begin to fluctuate - magnetic clutch stops between 2700-2800. After 2500, A/F ratio's drop to [12.5 -11.8] Dropping rpms after 2800 - magnetic clutch starts causing A/F raito's to go lean again.

Using the shop manual/search function and speaking to the only certified rotary mechanic in Denmark. This is what I have check as of today.

Air pump (F-121):
Disconnected connector (pumps stops) tested continuity (good) Swapped air pumps and have the same problems.

Air pump relay (F-123)
Ignition on/off (clicking heard) tested continuity (good) have not tested SV (relief 2) next on the list.


Other area's that have been tested/ replaced or in working order to specs-
TPS
Map sensor
Air relief valve (F-118)
ACV - (replaced last year)
Purge tank
Dash pot
Water temp sensor
Intake sensor
PVC valve
O2 sensor
Wax rod - throttle body
ISC
Spark plugs (9's)
reset pfc
PFC readings p.35 all check out within spec

'94 with 40,000 miles/stock motor/stock turbos
Related mod's- PFC/intake/high flow cat/catback/med intercooler/ Egde tech Wideband

I still have other areas in the secondary air injection (F-119) that need to be tested. Hope someone could double check what I have done (tested or not tested) and give me some good suggestions or reasons why the magnetic clutch is acting this way? I have a smog test the 27th and it's not looking good.......

Best Regards

 

how are you measuring the a/f ratio?

 

Hello Mad_7tist
I am using the Tech edge wideband unit
I just noticed I spelled it wrong in my first post - under my mod list

Here is a link to my unit - http://www.techedge.com.au/vehicle/wbo2/

My understanding is the air pump magnetic clutch stops at 3250. During deceleration, the air pump should also come back on at 3250 or in that area. My clutch switches on and off within a 400rpm gap (2400 to 2800) This sends my a/f ratios bouncing around lean to rich. Using the pfc fuel correction - I can't get the ratio's to settle to stoic 14.7 with the AP clutch acting this way. It's again, to small a gap. For a short moment during cruising I can see stoic ratios but not in neutral where they test emission here.

I wish I understood more, how the magnetic clutch gets it's signal to disengage and activate. The AP relay checked out but I will test everything again....

Mad-7tist or others...... any suggestion?

Thanks

 

if your testing on a dino the rpm range is normally under 2200 rpm. Between 1800 and 2200 is where most FD3S come in.