RotaryJohn

1993 FD MT, 187,000 miles (44,000 miles on 3rd engine). I don't work on my car.
Last week I had the following preventive maintenance done at a Mazda dealer: change engine oil & filter, change transmission and differential oil, new fuel and air filters, flush cooling system, new radiator (engine runs 15 degrees cooler), new coolant thermostat, new metal AST, new radiator/heater hoses, compression test (118 psi, 116 psi), new spark plugs/wires, inspect fuel injectors & pulsation damper for leaks (none found), test flow rate of OMP (OK), new belts, new O2 sensor (Bosch). They also replaced a bad throttle body gasket. Upon driving the vehicle after this service, I found that the engine would sputter and stumble badly and lose all power in 2nd, 3rd, 4th gears at ~5 psi boost on my boost gauge, as if its not getting any air/gas. Lifting off throttle restores normality. Engine runs fine otherwise. This problem has never happened before. Dealer has had car last two days but is clueless.

AE_Racer

iTrader: (1)

Well they touched a lot of stuff. It sounds like it could be in limp mode. Even if you don't have a check engine light I would check for codes.

Molotovman

iTrader: (49)

Do you have the invoice to post and do you have a Wideband O2 sensor?

Red94fd

iTrader: (5)

Thats a lot to troubleshooting to do.
Vacum leak,?
Spark issue?
Fuel system issues?
Check to see if its in limp mode as suggested.
Look for anything lose.


Never take your car to the dealer.. lesson learned.
Good luck man..

RotaryJohn

Three different dealer mechanics from two different dealerships were unable to fix the problem over a two-week period.

I went to Banzai Racing. In an hour and a half they found and replaced several flaky check valves and vacuum lines, which fixed the problem.

Sgtblue

iTrader: (16)

Glad you got it sorted.
I remember checking voltage and checking nozzles by blowing thru them, but didn't know the actual flow rate of the OMP could be tested.

Banzai-Racing

iTrader: (11)

Glad I could get it sorted out for you.

will7

Dealerships aren't the way to go.

bearbrik

Especially with a rotary

GC BUTTER

Recommend Banzai Racing. I've used them before and they know what they're doing!