Does the TPS affect when the secondary injectors come on?
 

What is the function of the TPS in relation to the ECU? does it tell the secondaries to come online at heavy load or am I thinking completely wrong?

Yup I would think so.

The reason I'm asking is that I switched harnesses and injectors on my 88 yesterday. The project went great but now I hit a brick wall when my secondaries come on.

they should come on weither the tps is pluged in or not..

I would just look at your injector wiring it self.

One of the functions of the tps is to show the ECU when the throttle isn't moving, i.e., cruising on the highway. Once the trottle is still for 3 seconds, the ecu goes into closed loop operation where it starts sampling the O2 sensor and trying to setup the most economic fuel arrangements.

About the pressure/boost sensor. Does your new harness have the identical number of wires going to it as the old harness?????

Did you make sure that you attached the ring connector that has the grounds for the ECU down with a bolt??? Its located on top of the block. Just a touch to the left of centerline and a more towards the rear of the engine than the front.

Will your car reach 6000 rpm by gently applying throttle ? Verses stomping on the pedal??

If the vacuum hose is disconnected from the boost/pressure sensor, then the secondary injectors will come on at 3500 rpm each and every time you reach that rpm. If the pressure/boost sensor is intact and all hooked up...the secondary injectors will come on only if you reach 3500 rpm AND the boost/pressure sensor senses a LOAD.

There are several things that control when/if the secondary injectors come online. The above is the primary scenario. See the 89 manual and the RELATIONSHIP page in the FUEL section. There's another relavent page I can't remember the name of.

Here is the Chart. There is a better one in the manual close by to this one. Don't pay attention to what I circled in red. That was for another thing.
https://www.rx7club.com/forum/attach...&postid=871818

ok well first off the ground for the ECU is connected. I know that because at first it wasn't and it was causing problems. The car will reach 6000 rpm if i rev slowly so i figured it was the secondaries. i went outside and tested the secondaries and one had a very faint click in relation to the other. I pulled that one out and swapped in another one that I had . The car no longer hits a Wall, but it still sputters now after the secondaries come on. I'm thinking maybe I have a clogged injector now? as for the pressure sensor, That is the sensor thats against the passenger side strut tower correct? It's vaccum line is currently running to the nipple coming out right above the ACV

alright now theres a change, The car will now easily rev to max rpm until you put a load on the engine, then ther's a sputtering when the secondaries come on. So i dont think thers a problem with the new injector itself

are they the stock size or did you put bigger ones in?

these are the stock injectors. I swapped in the complete harness also with the resistor pack to bring the injectors up to 12 ohms

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***alright now theres a change, The car will now easily rev to max rpm until you put a load on the engine, then ther's a sputtering when the secondaries come on. So i dont think thers a problem with the new injector itself*****

Good. Progress is being made here. You won't like the recommendation though. I think its a grounding problem. No. Not as in adding more grounds to the engine, but you should check and see it the original ones are on.

I suggest going to the ECU. Pulling the three plugs off. Grab the small plug. Unwrap the insulation until you uncover the wires about a foot from the plug. There you will see where the black wires are meeting a crimp splice. Get a good soldering iron and some good soldering paste and heat that thing up. Solder a 16-18 gauge wire to the exixting black wire and splice. Now connect the other end of the new wire to a ring terminal and attach that to one of the 10mm nuts that hold the ECU to the floor board.

The hesitation WILL stop.

If you don't like this answer.....then think. Did you really attach the ground ring on the top of the engine good?

Sorry. But this is one of my BEEN THERE DONE THAT posts. I have one car that is/was a lemon. The only thing that stopped that hesitation was what is described above with the solder job. And my ground ring on top of the engine was on good. All I have to do to make the hesitation come back...is take that new ground ring off the 10mm head size bolt that hold the ECU down off. Then 'ole Buck comes back with a vengence. My other two cars do not/never have exibited this problem. Just the lemon car.

thanks for the advice hailers. First off let me preface this by saying I really dont mind doing the electrical stuff. I started learning about cars while installing stereos and alarms. Now I know that the ground that you're speaking about is connected. The ground was not connected at first and I was having problems everywhere. I determined that the ground was not connected and I was able to bend out the bracket that holds the spider to the intake plenum. I then connected the ground to that bracket ( Maybe not a good enough ground?) After connecting the ground I had that problem with the bad fuel injector, now that thats corrected this is the last problem I'm having. Before I go down and do some soldering let me just give a bit more info. I do not think that the car is sweeping smoothly anymore. Maybe I was just blasting through the stutters that were ocurring. The car sputters whether it's under load or not. Obviously more noticeable at load. In addition, My AFR gauge is all whacked out. It's giving all wierd readings which I think may also be attributed to a bad ground. With this new info do you still think that the ground is the way to go? By the way, How did you determine that the ground was the problem with your car?

Also I want to reiterate that at load, It is not a buck like it was with the bad injector. It's more of a sputtering and a lack of power.

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I determined the ground was bad on my car by.....suffering through unmittigated hell for a long, long, long time. Then one fine day while searching the web I found a post/thread by RXSTR down in Florida. That thread was in this archeive for second gen cars. So I took the plunge and crimped (I was having soldering problems so I crimped first) a 16/18 gauge wire onto the splices in the harness and terminated it on one of the ECU mount bolts. WAlla! No more hesitation, stumble etc. Since then I soldered a wire to the black wires and kept the termination at the ECU bolt.
That was on a 87n/a car. I put a turbo engine in that car last spring and during fumbling around left the ring terminal off the ECU bolt. I got hesitation right around three grand and a stumble at 3500 which seemed to clear up in the higher rpms. I think the secondarys just masked the problem at higher rpms. I put the ring terminal back on and WALLA once more. Smooth, normal acceleration and its noticable at the higher rpms also.

I have two other cars that have NEVER exibited this problem. One is a early 86, which should have exibited it but didn't. Mazda was supposed to have corrected this problem by the 87 model year.

It sounds like your grounds at the top of the engine are good. So were/are mine.

Then again it could be a seperate, non related problem that you are experiencing. You might try it once you've tried everything else under the sun . I know it can't possibly hurt a thing. Nothing to lose but time.
Unmitigated...is that with one or two *t*s?

By the way. That ground was the second best thing to happen to my car. The very,very best was installing two new relays in my wiper switch so that they worked right. For some reason a half ass working wiper just bums me out.

well I haven't been able to solder the wires yet because it's been raining for 2 days. I think that we're on the right track though. I was reading someone elses post who was having problems with the summit switch. In that post, I believe you replied and suggested to remove his boost/pressure sensor vacuum line in order to force the secondaries to come on regardless of load. I attempted the same thing to force them on and it ran even worse. But then I reconnected the vacuum line and it ran better. Today I drove the car to the Bronx and it felt like crap on the way down. I pulled over and checked the boost sensor vacuum line and thats when it hit me. It was not the state of the vacuum line that had made the difference the night before, but rather the fact that the boost sensor was spinning freely on it's mounting nut. I could only assume that this is probably an ecu ground point. I tightened the nut and it feels much better. It is by no means fixed but I think the ground will solve the problem. By the way did you read about my afr gauge? A bad ECU ground could potentially whack it out, no?

Thats my car right there.. if I go really slowly I can make it up to 6k.. but if i mash the gas it sputters and rpms bounce at 4kish.

i'm hoping its just the grounds =/ any ideas?

ok so after work today I took a look at the harness. I was not able to find the bundle of grounds so instead i tapped the grounds at the ecu. I only re-grounded 3 of the four because I didnt have the FSM with me and couldn't remember the fourth wire. The car runs MUCH better. I would tell everyone to add some grounds to your ECU. But I am apparently still having issues. The car has very little power un the top end. It kin of feels like the HP and torque curves go flat at about the time the secondaries come on. I suspect maybe the last of the 4 grounds might fix this? In addition, my AFR gauge reads full lean or nothing at all when the secondaries come on line but if I back off the throttle just a little bit, the reading comes back and is usually in rich territory. The no power problem that I'm having seems to be more apparent as I go through the gears, in first gear I don't really feel it and second is more noticeable. Could this be indicative of a non functioning 6PI system or perhaps a vacuum problem? I'm going to reground that last wire and update

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Maybe the auxillary ports are not opening?????? I used to put a long vacuum hose on the inlet nipple for the aux ports and blow as hard as I could. They should open doing that. If not...they are a bit stuck. That's on a 86-88 car. Series five work just a bit different. Not much.

Or use a shop air hose and offer it up to the inlet metal nipple for the aux ports and they should move. You don't need a air tight connection. Just point the shop air at the metal nipple opening.

If they don't open, try to fix them. The little *pots* or actuators are fairly sturdy outfits. I had one that you couldn't move with hand pressure, and removed it and rapped it on a piece of wood til it free'd up. It worked under human air pressure after that.

I, at one time had my wideband connected to the n/a car and what little I remember is.....I never saw a lean condition at full throttle. Around five grand there seemed to be a rich spot b/t 5000 to 5500 and then it would get into the low thirteens (this is memory, no notes taken, but it sure was not lean).

Even before the wideband, I had a digital voltmeter tapped into the 02 wire and at wide open throttle on the n/a I'd see .7 to .8 volts.

The grounds shoudl be on 3G, 3A, 2R and 2C. The counting is from looking at the rear of the plug where the wires go in, and the counting starts from the far right of the individual plug to the left. In a up/down fashion. The small plug is 3 the middle plug is 2 and the plug to the far right is ...........

Try buying some wire taps from the RAdioShack and install one on the 02 wire right at the ECU. Then connect a digital voltmeter to it and let the car get fully warm/hot. At idle with a stock/operating acv/airpump etc, you should see a very lean reading. That's due to the airpump air being injected into the exaust ports at idle.

At a steady 50 to 70, you should see the reading alternating on either side of .4 volts. At full open pedal to the metal, balls to the wall, you should see .7 to .8

On deceleration you should see squat or very, very lean due to the injectors shutting off during deceleration.

I never had a afr meter as you do. Just went from a digital meter to the wideband mostly to see how the afr looked on a stock turboii prior to any monkeying around.

It sounds like your car is doing better with the grounds. One other thing on my lemon car caused hesitation that came and went. It was that the secondary injector wires had been replaced. They had been crimped spliced on the harness. The crimps, although securing the wires where you couldn't pull them apart, made a intermittent connection. With a ohm meter I could manipulate the connection/splice and make the meter reading come and go. Soldered the same wires to take care of that problem.

ok, let me just say that Hailers , you are the man. I have not been able to check out the 6pi yet but i suspect that it may be the culprit. I will try some more stuff tonight and update the thread as I get more info. I would just like to thank you for taking the time to answer my questions, It's the guys like you that make me keep coming back to this forum. I love this place!