Today morning the Rex was just fine, I even killed a 600cc bike on the way to the office. When I left the office car was fine too (well, apart for the annoying sound coming from the air pump (???) sounding like a huge exhaust leak).

Went to pickup my g/f, and when I got in the car, I turned the A/C full blast. The idle has been a bit lumpy for the last 2 months, and with the A/C on its even worse (it'll surge between 600-1200 rpms like someone is giving it gas). After about 4-5 minutes I notice that the temperature is rising (probably the stock e-fan is not working at all), so I turn off the A/C.

From that point on the car will not make ANY boost. It will start to rise from -20 towards 0, but it will not go any higher no matter what. There is also a very loud "swooshing" sound (wastegate stuck, BOV stuck, HUGE intake leak ?????), and the car will not make it past 3000rpm very easily.

I've searched and I came up with either some intake hose HORRIBLY cracked (Which I dont think is the case here), or something else (some of the above that I mentioned)....

Any one has any ideas ?

 

No takers ? anyway....

Tried some things:

- looked for error codes: none

- while I had the connector grounded, I started the car to set idle speed. Holy crap, idle was barely 100rpm, and the BAC didnt seem to affect the idle speed as soon as I disconnected the jumper, idle returned to normal 750

- checked the duty solenoid (at least I think I did, FSM is very vague), found infinite resistance. Is this even possible ? Probably tested the wrong connector (although I tried almost every connector in the area).
What the **** is up with that ?

- listened for any vaccum leaks, couldnt hear anything. Tried with CC, no change in idle whatsoever. Checked to see if anything is disconnected, nothing too.

- only thing that could be heard is the noise that the air pump is making, sort of like a big vacuum leak (like a boat engine with no muffler).

The car will not make any boost. It will rise to 0, and then it will make a very loud noise (sort of amplified BOV sound) and not make any boost.

ANY ideas ? Maybe something very simple that I'm missing ?

 

Yep, as best as I could without taking the IC off....even tried that, but I dont have any heavy tools in my house, and the 9" bolts DONT WANT TO MOVE dammit.

As far as I could see, the IC hoses are fine...but I know now that I havent tested the solenoid valve properly. Will go back and test again....

 

sounds like a pipe blew off or something.. which makes sense, it raises from vacuum to atmospheric, then stays.

 

Probably.....I have tested the solenoid valve right this time, and got 37 Ohm, so solenoid valve is OK. Also tested BAC, and although it does seem a bit sticky (rather slow to compensate), idle does respond to BAC connector removal and reinsertion, so BAC is OK too....

Tried to find if any hose is loose or split, but couldnt hear anything over the loud swooshing noise. I really have to get the IC off, but I cannt because I dont have any heavy duty screwdrivers, and the IC bolts are next to glued

Cannt really do much now, because its starting to get dark...I guess I'll have to take it to the shop ONCE AGAIN

 

$100 says it's your intercooler piping...seriously

 

Don't take it to the shop. Buy a drop light, and work on your car in the dark, all of us have done it. Use an 8mm socket to get the IC clamps off, screwdrivers suck for hose clamps.

Pull off the IC and re-install it. You should paypal Jspecracer7 $100 after doing so.

 

I dont even want to count the times I've worked in the dark on a car (I even did so when I was in the army in a far-away outpost)
But right now my g/f is with me in my house to watch a DVD with me (so I cannt really leave her like that and go work on the car ) so I'll leave the work for tomorrow. Dont worry Jimmy, I wont drop off the car at the shop. I'll commute tomorrow, and when I get back I'll start some serious debuggin work....starting with the IC.

If all goes well, I'll SAY that I gave Jspecracer 100$, how's that sound ? Hell, I'll say that I gave him 200$....its only words anyway




.....sure hope its as simple as a torn IC hose....

 

Just teasin ya Ace, I know you can wrench, you used to drive a Honda, right?

My TII was doing the same thing last night, no boost. Get right up to 0, and then stop. I checked the IC and everything looked fine, but I removed it anyways. Checked around, nothing. Put the IC back on and BINGO!!!!!! Back up to 10 PSI.

 

I had something like this happen to me a couple of weeks ago. With mine, It turned out that the metal connector for the hose that runs to BOV blew out of the metal IC pipe. I guess from age and vibration, that pressed in connector (nipple) just worked its way out.

It went when I was flooring it off a light. Scared the crap out of me. The first thing I thought was that I blew an apex seal, but once I realized I was hearing an air wooshing sound from the engine, my heart started beating again.

I'm sure you already checked that BOV (or air bypass valve) hose fitting, but if you haven't, take a look to see if it is loose in addition to the rest of the IC piping.

Good Luck

 

Thanks

and nope, all connectors and hoses seem just fine from the "outside".....

Only one way to tell actually: have to take off the IC and check all hoses from the inside....

While I'm at it, I'll clean the IC, adjust TPS, adjust the dashpot (its a bit sticky), and see if I can check and clean the turbo as well....

Maybe something good will come out of this....

 

Well, I did do a lot of work (that is, all the intake system, turbo system, and various bits and pieces are off the car ), and have found the following:

1) Stock TID has a 5 cm crack right at the turbo end. It is on the top side, but of course was not visible when its on the turbo down there....TID mod seems mandatory now

2) The boost loss was due to the plastic hose right after the turbo, which has two outlets: one for the solenoid, and one for the Air Bypass Valve (BOV). The nipple going to the solenoid was COMPLETELY cracked (and off the main plastic body of the hose) It is evident that it had also cracked in the past, and was welded again Guess I'll have to buy a new one now...Anyone knows what's its complete name ?

3) All other hoses and connections are just fine

4) '89-'91 TPS is completely different from the '86-'88. It has 6 wires, and you obviously cannot adjust it in the same manner. Anyone has any ideas about how to adjust a '91 TPS (I know, I know, FSM says not to, but what the hell ? )

5) IC is just fine. Cleaned it, left it to dry. Should be in tip-top shape once again

6) Turbo is ROCK SOLID No play whatsoever, very free spin, no touching of metals (of course). Yeah....

7) Dashpot was a little loose. It had almost a milimeter of "space" between its nipple and the throttle. Adjusted it....

All in all, not a bad day's work coming home from an exhausting day at the office Only thing remaining now is to find out the cost of that little plastic hose and its little hoses going to the solenoid and the BOV....

 

Just got the little plastic funnel with the two connector for the BAC and the BOV (the plastic hose right after the turbo going to the IC, 10cm long). Dont know if this is right or what, but it costs 100 EUR God damn, Mazda is really making a profit selling parts for the Rexes....

I wanted to ask for the price of the stock TID, but the head mechanic (at a Mazda shop, no less) said "dont even try, they are hella expensive"

TID mod seems more and more the way to go

 

Read my post on this:
https://www.rx7club.com/forum/showth...lug#post427625

And follow up reading with:
http://www.johnr.com/tps.html


Use the meter method. I didn't outline adjusting the full range. That's covered in the other link.