weetbix13

hi everyone... my rebuild is on 1500miles... and tonight after a boost test run i pulled into the drive... idle was lumpy as anything and sounded very laboured.

i don't want this to be an engine, so i'm looking for reassurance based on the following:
- idle was lumpy but vacuum was dead steady - only moving when a/c or headlights were turned on... i mean dead steady
- i have 3mm rotary aviation seals in there... !!
- the car starts better than ever, no issues with turning over
- car runs perfectly once under throttle - no missed beats at all

i'm hoping you'll confirm my beleif that i have a rats nest leak... or that a housing and seal have just broken in... right?

RIGHT?!

MavrickFD

Did you check your MAP sensor? It might've popped off.

GoodfellaFD3S

iTrader: (213)

What is the vacuum, and at what rpm are you reading that vacuum?

weetbix13

-0.6 BAR at 800rpm

DaveW

The only sure way to know is to do a compression test.

themcneal

iTrader: (1)

I agree, check the MAP sensor hose, but .6 bar does sound low at idle.

I had my MAP sensor hose pop off this morning on the drive to work.

They might as well call the MAP sensor hose the "heart attack" hose, since until you stop the car and look at it, you don't know whether it's the hose or a larger engine issue.

rynberg

His symptoms are nothing like a popped-off MAP sensor hose. 0.6 bar = 17-18 in of vacuum, so there's no problem there.

It doesn't sound like a blown motor to me.

themcneal

iTrader: (1)

rynberg, my mistake on the bar conversion, I was converting to PSI, not in of vacuum, my bad, you are right.

NINjaX7

sorry to ask this question but where is the MAP sensor hose? i'm getting the same symptoms

1QWIK7

iTrader: (33)

^^parallel to the TB, on the firewall. Its a black plastic connector with a vaccum hose running off it.

weetbix13

the MAP is the #1 thing to know owning these cars... mine's popped off twice now leaving me counting the change in my wallet to see if i can afford a rebuild.
beleive me, you know when that sucker comes off... smokes black smoke like a frieght train.

have done a compression check 'by ear' and she is rock solid inside with a good solid chug on each rotor face... guess that leaves either idle control, TPS or vacuum leaks (my vacuum at idle is slightly lower than normal at that -0.6 BAR).

visual inspection of vacuum hoses they all look on... let the hunt begin!

*considers non-sequential conversion*

dgeesaman

iTrader: (7)

1QWIK7

iTrader: (33)

Damn i was close, its directly parallel to the intake elbow it looks like. But yeah, you cant miss that black connector on the firewall.

quicksilver_rx7

F.Y.I.
The O.E.M. MAP sensor is labeled as "Sensor-Boost" (a.k.a. "Boost Sensor") on the top of it.

weetbix13

sorry, d/p.
see next post for response.

weetbix13

ok, well, i figured out my airpump wasn't grounding through the switch... when i hard wire that, she runs smooth and perfect... this makes me think it is a clogging cat issue.

i'm going to hardwire that for my next few drives to get some air into that cat and see if i can improve it. i noticed looking under the car last night some grey smoke from the cat... i think it just hit it's last legs without the airpump!

any recommendations of a ignition switched 12v to wire the airpump to?

RX7Wishing

just ditch it.

RotaryResurrection

iTrader: (8)

No, the engine uses some air pump air to inject into the intake manifolds via the ACV. This leans the injected fuel out some (by adding more air) and smooths things out. Those who remove the air pump will always have a lumpy and rich idle because of it, until you get a computer to compensate.

A car with a stock ecu and a bad or removed air pump will idle rich and rough.