My car...bad moods! ?

[John Yorke]

Jap imports only have the one cat Dont quite understand your \'boost is caused by restriction\' though. A turbo compresses the air drawn into it then it is fed to the engine via the inlet manifold if one of your butterflys was not opening surely the engine would not rev at all :confused:

[Carl]

Boost is usually measured after the throttle plates,in the plenum,so you would not get a boost reading if your throttle was shut.
Jonh maybe right about the cat,they seem to play up as temps change in the exhaust.
Anyway if you are getting the boost spikes that you say you are on a stock ECU your engine won\'t last 5 minutes.So do something about it quickly.
You don\'t need to run a cat in the system,replacement pipes are not that expensive either.
Be aware that the RX7 FD is a high maintenance car in many repects and they do need alot of attention to keep them running right.
Regards
Carl

[Bobfish]

Boost is an indication of restriction.  lets say the turbos can move 10 cubic meters of air per minute.  If i force this through a hole that is 1cm round boost will be higher than if i put it through a hole that is 5cm round.

In this case i am saying that possibly some of my throttle butterflys are not opening, and because of this restriction is greater so although my boost is still 10psi, airflow is not as great due to increased restriction (due to decreased area that air is forced through)...do you understand?

[Bobfish]

Carl, i am trying to maintain her properly!

And also, i do not mean that all of the throttle plates are shut.  There are 3 plates in the throttle body, and some are controlled by the dual throttle system? if this is malfunctioning i am thinking that some of them are sticking shut, hence there is lesser area for the air to get through, this would cause a 10psi boost level to be reached quicker as there will be less potential for airflow...

[goose]

ive been told the two arms are for cruise control operation, but ive also been told that both arms should move together and im sure mine used to!

I was so confused by this, I went and double checked - mine definately don\'t move together (I\'ve got some phots to prove this). Anyhow, I think this is a red herring. As long as the cable moves the arm, which turns the shaft, which turns butterflies inside - that\'s all that needs to happen.

The pressure side of my inlet popped off due to sudden massive increase in boost pressure due to sudden massive increase in resistance due to one of the throttle butterfly snapping shut.  Thats my theory!

The boost should be relieved by the BOV, which is actuated by vacuum pressure caused when the throttles close. So unless this line has popped off, then this should be working.

I will check the double throttle control - whats the best way? Do you mean the arms SHOULD move together/ because mine never do, even with the car warmed up! how do i remove it?

Don\'t get confused here with the two throttle arms and the double throttle. The double throttle is a separate set of butterflies after the throttle body. It\'s on the UIM itself, rather than the throttle body and is controlled by an actuator on the firewall side of the UIM. Have a look at my homepage for pics of the double throttle (and it\'s subsequent removal!) http://homepage.mac.com/flobs/PhotoAlbum20.html

Dont think the vac lines are splitting - theyve never been replaced, but i dont seem to have a boost problem; the car is regulating boost perfectly, i get a 10 8 10 pattern (most of the time) it just feels like the car isnt getting enough air! (i.e some of the throttle butterflys are closed)

Im going to take the elbow off tonight and check that, check my spark plugs and wires and reset my ecu - then ill let you all know how i got on...

Hope this gets sorted soon, ive only just sorted my leaky coolant seal!

As mentioned earlier, there\'s a good chance that your cat could be toast, although there\'s no way of knowing unless you take it off and have a look. The Jap spec models don\'t have a pre-cat.

If the vacuum lines have never been changed, they\'ll almost certainly be hard as rock and will crack. This will cause intermittent and hard to diagnose problems. It would be worthwhile changing them all, which is quite a long job, but not beyond your ability I\'m sure.

Regarding the age of your engine, can I give you a word of advice? It\'s near the end of its life and sitting in a salty crate coming over from Japan for 6 weeks won\'t have helped things. Now, my car blew at around 65k, spitting out the apex seals through the turbo - which meant I had to buy new turbos as well as an engine! It may well be more cost effective to get a rebuild now, rather than risk damage the housings and other parts when it does fail.

But that\'s just my 2p...

[Bobfish]

thanks for the long reply goose!

I dont know what your referring too about boost being relieved by the BOV - thats not what i was getting at anywhere, i think you just got confused by my rantings about boost reflecting resistance.

How do i check the cat then? just shine a torch into it and check the cells look uniform?

The vac lines have never been changed, i know they cause problems! i dont think this is to blame in my case though because as i say, the car is regulating boost fine.  The vac lines regulate boost control dont they...so it would seem these are fine.  In any case, after i check my TB and cat, vac lines are next on the list.

I know what you mean about the engine rebuild too, i am going to start saving now for a rebuild kit, gonna do all gaskets seals and hard parts, trouble is i dont have £700 to spend at the moment with a possible further £900 of expense should my side housing prove to be out of specification (i will need new ones)

If it does all go (turbos too) i guess ill just have to bite the bullet and get a loan, although it is an excuse to build a streetported single turbo monster...

for now though, my agenda this afternoon (from 2pm on, the cars sat on my drive nice and cold ready to work on) is to check spark plug wires, cat converter, throttle buterflies, coils, DT actuator and solenoid, and vac lines in the rats nest.

I figure it HAS to have been something that caused a sudden huge spike it boost pressure though, as one of my boost pipes had totally popped off, and ever since the car hasnt been right.

[goose]

I dont know what your referring too about boost being relieved by the BOV - thats not what i was getting at anywhere, i think you just got confused by my rantings about boost reflecting resistance.

Well, I was referring to this:

The pressure side of my inlet popped off due to sudden massive increase in boost pressure due to sudden massive increase in resistance due to one of the throttle butterfly snapping shut. Thats my theory!

However, i think you\'re going down the proverbial garden path with the throttle bodies. They\'re pretty robust, so I wouldn\'t expect them to be a problem.
Once the throttles snap shut, negative pressure (vacuum) is produced in the UIM, which is picked up by the vacuum pipe, which in turn actuates the BOV relieving the pressure in the intake between the turbos and the throttle.

How do i check the cat then? just shine a torch into it and check the cells look uniform?

Yep!

for now though, my agenda this afternoon (from 2pm on, the cars sat on my drive nice and cold ready to work on) is to check spark plug wires, cat converter, throttle buterflies, coils, DT actuator and solenoid, and vac lines in the rats nest.

I figure it HAS to have been something that caused a sudden huge spike it boost pressure though, as one of my boost pipes had totally popped off, and ever since the car hasnt been right.

Looks like you should crack it once you get in amongst it!

I know my car overboosted when I left off the wastegate control line. May be a good one to check.

[Bobfish]

Yeah i suppose i know what you mean about the dump valve, and in a normal situation yes this is true - however my theory is correct on what im referring to; but its feasability depends on control systems.  Assume the two throttle control arms move together, one controls one throttle butterfly, the other controls the other two butterflies.  Car is boosting 10psi at WOT with all 3 butterflies open.  The rod (or whatever it is) connecting the two arms together snaps/falls out, and 1 or 2 of the butterflies snap shut, but one remains open.  This would cause a huge increase in boost pressure due to the increased resistance (or decreased potential airflow) through the remaining open throttle butterflys, but the DV would NOT operate due to the fact that the UIM is still pressurised as there is still a butterfly open.  The turbos would take a few seconds to spin down and adjust (as we all know the wastegates arent the best and would take a couple of seconds to vent off that extra boost) and as such would carry on producing 10psi of boost based on the airflow capability of 3 open butterflies.  This would be a much higher level of boost (from the turbos to the butterflies) and as such would cause a hose to pop off.

Do you understand? the above is assuming that one throttle arm controls 1 butterfly and the other controls the remaining two.  I understand this may not be the case but i thought id explain my theory!  Now can you can see why this would cause the boost pipe to pop off...a handy safeguard actually! (if this is the case)

Where is the wastegate control line?

[goose]

Assume the two throttle control arms move together, one controls one throttle butterfly, the other controls the other two butterflies.

But this is not the case. Both throttle control levers act on the spindle which has 1 butterfly mounted on it and a linkage on that spindle then acts on the other 2 butterflies. It becomes clear when you take the elbow off and have a look.

Car is boosting 10psi at WOT with all 3 butterflies open.  The rod (or whatever it is) connecting the two arms together snaps/falls out, and 1 or 2 of the butterflies snap shut, but one remains open.  This would cause a huge increase in boost pressure due to the increased resistance (or decreased potential airflow) through the remaining open throttle butterflys, but the DV would NOT operate due to the fact that the UIM is still pressurised as there is still a butterfly open.  The turbos would take a few seconds to spin down and adjust (as we all know the wastegates arent the best and would take a couple of seconds to vent off that extra boost) and as such would carry on producing 10psi of boost based on the airflow capability of 3 open butterflies.  This would be a much higher level of boost (from the turbos to the butterflies) and as such would cause a hose to pop off.

Where is the wastegate control line?

What you are describing here would more likely be caused by the Double Throttle closing when not required. Again, this could well be a control line problem.

If you get a copy of the factory manual there\'s a pic of the control system, from there you can work out which line is which. I\'ll post one up if you haven\'t got it. Once you get the UIM off, which isn\'t too much of a job, you should be able to see most of the obvious nasties which are causing your boost problems.

My money is on the control lines though!

[Bobfish]

thanks, if you could like the diagram itd be great!

[Bobfish]

i think i might take today as an opportunity to take out the main cat too...ill just weld another pipe to the flanges

Will this cause boost creep?

[goose]

Download the manuals from here:

http://www.iluvmyrx7.com

Lots of good stuff!

[Bobfish]

Lots of good troubleshooting stuff there, but i cannot see the map that shows all the vac lines and where they connect! Do you have this?

[goose]

It\'s in there somewhere, but just to make it easy for you try this link from the master of the RX7:

http://www.scuderiaciriani.com/rx7/vacuum_hose_replacement.html

Nice pretty colours too!

[Bobfish]

damn man...well ive pulled my UIM!

Broke a check valve and a solenoid nipple in the process (ironically the DTC solenoid) and cant realy see anything wrong to be honest. a few hoses have chaffed a bit but i cannot see any holes or cracks in them.

Im currently trying to source some check valves as i want to replace all of these, then i will replace the pipes i can and put it all back together.  I dont really fancy removing the rats nest and doing the whole lot, although i am going to think about it tonight.

3 weeks ive had the car and off the road already oh well! what can you do....