Troubleshooting with Dale Clark...
 

Well I just got in from troubleshooting my car in Pensacola today with Dale Clark. As many of you know I have been battling with my car for about 10 months now trying to get it to perform the way it should. After a motor rebuild, new turbos, and a ridiculous amount of other mod's this past summer the car still does not peform. To sum it up it basically comes out the hole pretty strong and then falls on its face in the mid-range. Although, after transition the car pulls like gangbusters. I believed this to be an ignition issue, so I have replaced or swapped with working parts everything that has to do with ignition. I have replaced everything from the plugs and wires, all the way to every coil pack.
So, today I arrive at Dale's and we take off the manifold and start looking over the vaccum lines etc... Then we do some vaccum testing on a few solenoids and found that the turbo control solenoid (the one located on the bottom of the manifold) seemed to test out a bit strange. It did not appear to want to hold vaccum, but would however snap open and closed when tested with 12 volts. Now im starting to wonder if my problem is not to do with the fuel or ignition, but possibly in the control system. So, tommorow I ordering that turbo control solenoid, and the solenoid that is down in the rats nest.
Also while in the process of doing the troubleshooting today we replaced my one way check valves with the "Viton Check Valves" that Dale has been selling here on the forum. I must say that this did not fix my problem but it did make a noticeable diiference in my boost response which I think is going to be even more great once a pinpoint and fix my underlying issue. So on that hand if anyone out there is running with the old ass stock one way check valves, I highly reccomend purchasing some new "Viton Check Valves" from Dale. It is a very cheap and easy way to help with your boost response... Also, if anyone has had any issues with the turbo control solenoids please give any advice you may have..... Thanks Jamie...

any help or advice here guys?

No experience with turbo solenoids here, but I just got into the vacuum hose replacement today; in 5 hours I managed to get the airbox, airpump, alternator, all ducting, and the throttle body removed. Anyway, I had bought 4 of Dale's check valves, and plan to replace my OEM types with those. Now I know why it's called a rat's nest... jeez, what a mess. Getting that bottom coolant hose and the electrical connector off the throttle body sure was fun... Rob Robinette and the other gurus never mentioned the cruise control connection... that was wonderful, too. Tomorrow should be fun, removing the UIM.

---- Bill

Yeah I remember doing the line job myself. It was a very time consuming and needless to say A Painful Job. My lower back and thighs were killing me for a week.... Good luck, you will tell a difference...

Well, if you're getting evidence that the TCA is leaking, or one of the TC solenoids is failed, then replacing it is truly an important step.

Dave

I use to have those boost problems so much that it forced me to spend money to go single and now no more problems and I only have like 4 vacuum lines to mess with.

Ehh, the complexity stock turbo system is part of its charm :)

(I know I don't say that though when it's misbehaving)

I would never be able to go single when there was a problem with the original that would be a $50 fix.

Does anyone here know if the turbo control solenoid that is located where the lower manifold and the upper manifold meet is supposed to hold vaccum? When we tested it yesterday it would not hold vaccum, it would snap open with 12volts but not hold vaccum. I ordered that one and the one that is located on the solenoid rack that works in unison with it today while I was at work. They only cost me $39 each, sure would be nice if $80 dollars fixed my problem after spending thousands troubleshooting....

Does anyone know if the turbo control solenoid that is located where the lower and upper manifold meet is supposed to hold vaccum. We tested it yesterday and it would not hold vaccum, it would seem to snap open using a 12 volt source but would not hold boost. I ordered that solenoid and the one that is located in the rats nest that works in unison with it. They only ran about $40 a piece so hopefully this $80 order will fix my problem that I have spent probably a couple thousand on troubleshooting....

On page F-176 of the FSM, it calls out the inspection process for this solenoid (item 8). Unfortunately, it's not configured like the other rats nest solenoids, so the inspection on this page isn't very helpful. I didn't find an explicit detail in Vanditmar's site either. However, F-93 shows the testing of the duty control solenoids, which are very similar in design. From that, it's clear the solenoid should not flow vacuum when there is 0v. It should only flow with 12v applied.

For the one on the rack, check out page F-176 of the FSM. The line running from the TCA goes to the rats nest TC solenoid top nipple. With 0v, it should flow to the filtered nipple on the connector side. Therefore it would not hold a vacuum. With 12v, it should open to the other nipple, which is connected to the pressure chamber. As long as the pressure chamber is charged, it should vent pressure when 12v is applied.

Last but not least, check out the posting by:
Date: Sat, 5 Sep 1998 11:41:28 -0500
From: "Steve Wynveen"
about halfway down this page: http://www.fd3s.net/boost_problems.html

Steve Wynveen (a former owner of my car) ran nearly the exact same troubleshooting issue you are now. So while waiting for the new parts, I suggest conducting his test sequence.

Dave

Throw your car on a dyno and see whats really going on. If boost is staying up but your still not making any power my guess would be that your way rich down there. Do you have an aftermarket ECU?

F the dyno - what is your 3rd gear WOT boost pattern? It occured to me the other day that you didn't specify it, but it's really the info to know. The dyno is a waste until 1) you know you have a good boost pattern, and 2) you know you're not getting boost creep or boost spikes. If you have any boost spikes or creep you'll blow the engine on the dyno.

Dave

My boost pattern is fine and I have a manual (Sears) controller on it right now to control the spiking... But to answer the question, my pattern is solid.

So where you say it falls on its face in the midrange, how low does the boost dip?

Dave

He said the boost doesn't dip. Think about it logically. He has air (10psi), he has spark (according to him), the only thing left is fuel. When a car falls on its face and still maintains proper boost its generally a tuning issue (to much fuel).

He doesn't have a boost problem buddy. Go back to watching and taking notes a little longer before you start giving advice.

Ya, dynos are usless for tuning / troubleshooting. ????

Anyways, throwing your car on a tuners dyno would allow you to see what was happening with your air/fuel, ignition, boost, egt, and many other things (all in relation with one another). Dynos can be great tools for solving little problems like this.

Boost always dips at transition. Until I know for sure it's hitting 10-8-10, or 12-10-12, or whatever it's tuned for, then it's rather obvious that if you feel a loss of power, boost is the first place to look. If he had said the boost pattern was 10-8-10 I wouldn't have wasted my time, and I hope he wouldn't have wasted money on solenoids. This is why the boost pattern is the first question in troubleshooting a power problem. Maybe Dale remembers the boost pattern.

What's he's describing might make for a 10-5-10 - which would indicate a boost problem. The fact that the TC Vacuum solenoid isn't shut at 0v sort of screams it.

Dave

Do you have a Datalogit or at least a wideband? Can you borrow both or either? Did you replace the ignition harness? Main harness (gets very brittle) ?

off the topic, but what kind of sideskirts are those, veilsides?

I have yet to do a leak down test or any test of the injectors. But, I have checked the volume and flow rate of the fuel system and it checked out fine. I have been suspicious of possibly having an injector problem, but not until last week when I installed the new leading coil pack. After I installed the leading coil pack, I changed the oil and filter and changed the plugs. Afterwards, not initially but the next morning after I had taken the car driving for awhile to see if the coil helped my car now seems to somewhat smoke at idle. The smoke I am suspicious of because until this point my car has never smoked, everything is new under the hood. So, I wonder that maybe after installing the coil pack and letting the car see some boost that maybe I helped an injector on its way out. If you have any input its appreciated...

From the problems he's been having, I've been suspicious of the turbo control valve's control system. Basically the car makes full boost down low, but the car bogs and feels slow. This is making me wonder if the turbo control valve is staying open - both turbos get the full exhaust flow so the first turbo doesn't hit as hard.

There are 2 solenoids called turbo control solenoids. One is down in the rack with all the other solenoids, and is just a "plain" solenoid. The other one is duty controlled and is mounted on the air control valve. The duty controlled solenoid has 2 nipples, yet also has a 3rd nipple (that sounds funny :)) that has an air filter on it. I pulled the filter off and tested it with the Mityvac - it will only hold 10" of vacuum one way (any more quickly bleeds down to 10") and will not properly hold vacuum the other way.

Unfortunately the shop manual doesn't have a clear diagnostic for this check valve. The test procedure for the other duty cycle controlled check valves doesn't really work, as the third nipple with the air filter goofs up the equation.

I think Jamie (DVSSeven) ran into something I've hit on rebuilds before - a car that generally runs OK, but a whole bunch of small problems that you have to track down and chip away at.

BTW, thanks for the endorsement on the check valves :).

Dale

Lopedl, yes those are veilside skirts I have the full c2 kit molded with custom paint. And, of course your welcome Dale not a problem at all.

Technonovice, just to answer your question, yes I did replace the coil harness with a brand new one. I have not replaced the actual complete PCM harness, I have spoke to Cam at Pettit, and spoken to Rob at Pineapple of whom built my motor and they say that I would be throwing codes if it were a faulty harness. I have not had the car throw a code since I put in the new motor and turbo's...

dgeesaman, my boost if I remove the manual controller is like about 12-10.5-13or14, which I know shows that I have a spike. But im not worried about that, thats why I usually have the car running at about 8lbs, or I simply do not WOT after transition. Listen, I know how a modded FD with mods as I have should run, and I know there is a dip at transition. This is not my first rodeo, im simply asking for some assistance.

pull the hose off the fpr and see if it has fuel in it. since it is a bitch to get to do it on the ecu side but ohming the ecu coolant sensor would be worth doing if you still feel you are running a bit to rich also

My aggravation wasn't directed at you, it was directed at Bee, who seems to think it's sensible to recommend putting a car on a dyno without any knowledge of the boost pattern. I figured you and Dale wouldn't be going that direction without such info, but that fact was simply absent up till now.

The turbo control vacuum side solenoid (the one on the ACV, see picture) is definitely not listed in the FSM for testing. I don't believe it's a duty-controlled solenoid, either (only the PC and WG pair are). It's either 0 psi or full vacuum at 4500+. But I don't have one in front of me to investigate. It's almost as if Mazda only intended for one solenoid to run the TCA, they added it at the last minute, and they added it to the pictures but not the text. I suggest comparing the operation of it to the new one you said you ordered, or just swapping them out since this solenoid is a common failure point.

So anyway, if you are sure you're getting a normal, full boost pattern, and the transition dip does not correlate with your hesitation, then I feel the turbo controls are all good. All the turbo control system can do is ensure the correct pressure of charge gets to the intercooler. Ignition, injection, air intake thermosensor, MAP, etc are where to go next.

https://www.rx7club.com/attachment.p...hmentid=110668

Dave