jusmyn808

Hi

I've been looking on all the rx7 forums and I'm out of luck. Please help.
I have a 93 rx7 twin turbo completely stock. A new 13 b.
I have done the following, replaced spark plugs and wires,checked fuel pressure-ok, vaccum, replaced tps sensor & adjusted, smoked tested for vaccum leaks-no leaks found, tested boost sensor-working fine, vaccum pump is running all the time-not sure if this is supposed to happen.
I have even grounded the engine and everything else.
I can't pull any engine codes, but I have pulled codes before ; so I know that's working.
My instrument cluster is working, while driving my car will not go past 3500 rpm it will miss and backfire. While revving it up in neutral it will rev to 4500 rpm miss for a second then rev to redline. Some times after warming up it won't rev past 4000 in neutral.

I've been looking on all the rx7 forums to find similar problems and I have been going in circles. I was told that RX7 CLUB was the place to come, Please help.
I have a 93 rx7 twin turbo completely stock. A new 13 b as the old engine was locked up from sitting for 9 years.

From what I can remember was the car was running, but it didn't seem to be running at the fullest potential, I brought it to a auto shop, and they told me I needed a new engine. I purchased a new engine from atkins rotary and the engine sat in the crate for 6 years. It took 3 years to get to where I am at now because most of the parts was just weathered. Parts for this car was hard to find. I also had to purchase the original 93 RX7 workshop manual, vacuum diagram, and wiring diagrams.

On January 9 2011 I got to start my car for the first time. The engine ran and sounded fine. I drove the car about twice a week for a month and then I wanted to order a blow off valve. Instead of doing that, my bf decided to unhook the charge relief off the intake box. The car drove fine. Finally I had my car painted, and when I drove my car it was fine, until a week later when I was driving it started to miss and pop. It wouldn't go past 3500 rpm.

I have done the following, replaced spark plugs and wires,checked fuel pressure-ok, vacuum, replaced throttle position sensor & adjusted, smoked tested for vacuum leaks-no leaks found, tested boost sensor-working fine, vacuum pump is running all the time-not sure if this is supposed to happen.
I have even grounded the engine and
I can't pull any engine codes, but I have pulled codes before; so I know that's working.

My instrument cluster is working, while driving my car will not go past 3500 rpm it will miss and backfire. While revving it up in neutral it will rev to 4500 rpm miss for a second then rev to redline. Some times after warming up it won't rev past 4000 in neutral.

7/14/2011 - We have checked for exhaust restriction, and with exhaust it is still missing. The fuel smells rich, and again at WOT it misses.


7/20/2011 - Replaced the TPS.



7/25/2011 - Since my last post, I Changed metering oil pump, and same problem. Checked the turbo precontrol solenoid, checked pressure chamber, tested the secondary injectors, ohm ignition coils-ok.

Its still doing the same thing. Bucking, smells like its running rich, and at WOT will not go past 3500 rpm it will miss and backfire, but if I slowly accelerate it will go past.



I can send videos of the tach bouncing/jumping, and of the engine while this happens.


Any help would be greatly appreciated

limepro

iTrader: (2)

Have you checked all of the vacuum lines? I would suggest checking them and replacing any that are not new. I am not 100% but unhooking the charge relief without something in place may have put you in limp mode, I would suggest keeping the bf away from the car and either doing things correctly or not at all.

limepro

iTrader: (2)

I was also curious how you are pulling codes? Are you doing the light test or do you have the mazda scan tool?

crash x 4

Do you know if your running a stock ecu or a aftermarket one? Have you done a compresion test yet? does the jumping and jerking happen all the time or only during certain rpm ranges?

limepro

iTrader: (2)

I am guessing it is in limp mode, if you can pull the codes you would most likely get a code in the 40's for the charge relief.

Mahjik

iTrader: (1)

A few things to check:

1. Check the water thermosensor and the fuel thermosensor. Make sure (by wire colors) that you have the connectors on the correct sensors. The sensors are close enough to mix up the connectors (and they are same physical sensor).

2. Check the CAS connectors. They can be inadvertently switched as well.

In either of these cases, the car will idle but will not rev properly. Neither of those will throw a CEL.

getgone

iTrader: (2)

As usual, Mahjik has some solid suggestions. Also check that you have the correct wires on the actuator control solenoids at the front of your UIM (the green ones sitting side by side). Depending on the age of your car, there should be a white dot on one of the connectors that corresponds to a white dot on the correct solenoid.

jusmyn808

Hi all the vaccum lines was checked with the smoke testing thingamajig and all the lines are brand new.
if I am in limp mode how do I get out?

jusmyn808

I am pulling codes by doing the light test, and I know its working because we purposely unhooked something to see if it read a code, and it did.

getgone

iTrader: (2)

Also check to be sure the hoses are to the correct ports on the small manifold beneath it. Put the wrong hose on the wrong port many times while reassembling.

jusmyn808

I don't get any codes.
Engine Light not on

getgone

iTrader: (2)

Well, if you are in limp mode you should be throwing a code. But to get out, simply disconnect the battery, pump the brakes 20 times and reconnect.

jusmyn808

I will definitely check today.
I thank everyone for their time replying to my post.
I have the one and only rx7 on our island, and the car only has 40k original miles, with the new engine it only has 30 miles.

jusmyn808

Ok will do as soon as I get back to my car. Wow your fast at replying.
I appreciate it.

jusmyn808

Running stock ecu. Have not done a compression test, but will do one today, and the jerking happens all the time. Just sitting neutral and going to wot it happens. When it started happening I was on the main highway and I tried to floor it and it started bucking. I didn't want to drive it after that. pretty sad when everything else that shouldn't pass you did. Lol

jusmyn808

oh I forgot to add that it happens at about 3500 rpm and if I slowly accelerate it will go past.

RotoryDreamer

Just throwing in my 0.02. With only 30 miles on a fresh motor you shouldn't be driving it that hard. You should take it easy and try to stay out of boost for at least 300 miles before you start driving like you stole it. Otherwise it could lead to poor sealing and premature engine failure.

twinsinside

iTrader: (34)

If possible post up a video of the problem.

So the engine sat for 6 years before the install and then worked ok for 6 months before having problems?

During the paint job is it possible paint somehow got into your harness connectors?

Your secondary injectors could be having problems especially since they sat for so long.

I'd also check all of the ignition stuff like plugs, wires connected correctly, ignition harness, coils, etc.

And yeah, not a great idea to be going WOT on an engine that sat for 6 years 30 miles into it.

jusmyn808

So far, yesterday we checked the secondary injectors, and the wiring. Found nothing . Components working eyes fine.
I posted video on you tube under jusmyn808-1 and jusmyn808-2 I never used you tube before, and this is all new to me.
you guys totally rock for helping me.
Thanks again

jusmyn808

This is with down pipe/cat off
Engine
http://www.youtube.com/watch?v=cxSTs...e_gdata_player

Tach
http://www.youtube.com/watch?v=we7-q...e_gdata_player

mx855

I had this EXACT same problem with my car that just randomly appeared one day.

For me the car was hitting a fuel cut, with both a POWER FC and the stock ECU connected, in the same spot. If I remember correctly it had something to do with the 2 crank angle sensors, we rewired both connectors and ran lines directly to the ECU and it fixed the issue, but whenever the lines on the factory wiring harness were tested they were fine...

Instead of just rewiring the 2 sensors properly through the factory harness I just purchased another harness because the stock one was getting very brittle anyways, it solved the problem.

I would definitely say to check the wiring on the crank angle sensors... as with most FDs, the wiring harness gets so brittle that the wires crack really easily. (at least they do up in canada!)

getgone

iTrader: (2)

I would agree with mx855. You may have issues with the old harness and be further ahead just replacing it. Even if it does not solve the problem, a new harness is probably just a reality anyway. With all the heat these engines generate, the stock harness simply breaks down (loom, wiring, connectors, etc). I am on my second harness and am giving thought to replacing it again when I do my upcoming top end overhaul this fall.

MazdaSpeedDan

iTrader: (4)

Have you fixed problem OP?

GREG5656

My 79, 12A RX7's Tac pointer would bounce up to 1000 rpm's to 1500 plus and down again in less than a second time interval. The problem was not my wiring, it was the Distributor "Points Plate" that was lifting upwards by a 1/4 inch. Remove the 2 screws holding the plate down, and lube the bearing under it, and the weights also. (My bearing were bad, I did not feel a smooth rotation of the plate after lubeing it)...This lifting of the plate, caused the trailing points rub block to touch the cam prematurly, making the points open too soon. Test this by lifting the plate with your fingers at one end and watch to see if your points open and close. . .This opening made my RPM gauge to be unreadable, and Yes my timing was not the best and it really was the timing issue that led me to shim the plate which gave me a steady timing dwell and consequently a Tac that now reads steady. I shimmed the "Point Plate" with a thicker washer at the hold down screw, to hold it downwards preventing the 1/4 inch upward lifting, but, remember the plate must have a gap under it for the vacuum advances of the Leading & Trailing to move freely. Greg5656

KKMpunkrock2011

iTrader: (5)

FDs don't have distributors...