Recently installed my newly rebuilt engine and have a number of problems which I will address as I try to resolve them. Some I have already remedied. I am getting an intake air thermosensor code and have one coming tomorrow. The TPS will not adjust to spec, so I have one of these coming tomorrow also. The engine has only about 15 minutes of running time.

Current issues Im dealing with:
1. the purge control solenoid valve starts repeatedly cycling a few minutes after starting the engine.
2. engine starts popping and sputteringa couple minutes after starting. starts easily.
3. engine gets very hot quickly and I have to shut it down as it approaches 230 degrees. coolant level is okay and engine has been burped. cooling fans work okay and I have been turning them on when I start the engine.

chuck

 

On adjusting the TPS, if the fast idle cam is kicked in, the values will all be high. You have to kick that cam down and make sure the throttle is closed.

I have seen intake air temp sensors go out - good idea replacing that guy.

Onto your issues -

1- No idea. Not sure what's the normal cycling of it. I'd have to dig into the shop manual and see how that system works.

2. The popping isn't something too odd, especially if you have a high idle. If the engine is new, that's also gonna contribute to it running a bit rich and rough until it's more broken in.

3. Double-check your thermostat, and make 100% you're topped up on water. Pull the water line going to the throttle body - that helps get air out of the system. I've also used that line to fill water from as well.

Good luck!
Dale

 

Dale,
Thanks for the info.

I moved the anti stall dash pot out and the fast idle screw out to disengage those components from the throttle before testing the TPS.

As far as the thermostat, it was okay prior to the rebuild, but I will check it out anyway just to be sure. Also will remove coolant hose at throttle body just in case there is a bubble still floating around inside.

The solenoid cycling is a continuous click, click, click ...... seems that the erratic idling starts after that solenoid starts clicking. Ive been reviewing the service manual and vacuum hose charts to try to figure out what would cause this symptom and if the erratic running could be due to this component.

Tonite I should have the TPS and Air Intake Sensor waiting for me when I get home. I am going to recheck all my vacuum line connections and wiring while I have the UIM off to see if I missed something.

Throw more ideas at me. I would love to be able to drive the car this weekend.

thanks,
chuck

 

On the overheat issue, you didn't mention the "low-coolant level" buzzer going off, so I assume it hasn't. If that's true, and you've burped the system, I'd suspect the t-stat as well.
And when the IAT fails, it causes a VERY rich mixture. Not sure if it would make any difference, but wondering if you might want to replace it first, before dealing with any idle issues.

 

Jim, Thanks for the input.

The low coolant level buzzer went off the first couple of times starting the engine until I got it burped but hasnt been on the last few times Ive started the car. Was just talking to Jim Labreck and he mentioned exhaust bleeding into the cooling system through a bad seal - a remote possibility on a completely rebuilt engine but within the realm of possibility. Scary thought but I will have to check it out.

Well, I expected the parts to show up today from Malloy and they werent here when I got home tonite. Not sure what happened with my order. Im hoping Fedex delivers tomorrow.

The intake air thermosensor was first priority to replace to address my rich mixture and popping and sputtering problem at idle.

At this point, I have a pretty sweet looking engine to look at.

chuck

 

Since my parts didnt come this weekend, Im working on other problems. My stock low water buzzer and light work but the stock temp gauge doesnt register any movement at all. Fortunately, I have a temperature gauge that I installed when I bought the car.

Where is the sending unit that feeds the stock temp gauge?

I also vaguely recall reading something about two connectors being the same type of connector in close proxiimity to each other and that both were connected to a thermosensor. Im wondering if I many have reversed those and that is why the gauge may not be working.

Thanks for any feedback you may have on these questions.

chuck

 

That would be the Water & Fuel thermosensors. The fuel thermosensor is the one on the fuel rail and the water thermosensor is the on the back of the water pump housings. They are the same sensor so the connectors will work for either one. You'll need to check the wiring diagram to verify which one is which.

 

Is the water thermosensor on the back of the water pump housing the sending unit for the stock in dash water temp gauge.

 

No. The thermosensor is just for the ECU to activate the cooling fan relays.
IIRC, the stock guage sensor is a single wire located on the driver's side of the engine, toward the rear under the oil filter pedestal.

 

Ive got 3 wires that have a black plastic female spade type connection in that area of the engine that I have been trying to resolve. Two come off of the ignition harness and one comes from under the rats nest and extends over towards the oil pressures sending unit. One of those three wires connects to the starter and the other two I wasnt sure of. I believe I connected the one from the engine harness to that sending unit just behind the oil pressure sensor.

 

a3dcadman,
Sorry, I've never had to mess with the stock temp sensor. I only vaguely recall looking at it once or twice when I was under the car. Maybe someone else can chime in with more/better info on it and where the wiring originates.

 

Jim, appreciate your input. Anyone have any info on these wires and the stock gauge temperature sensor/sending unit?

Installed my new TPS last nite and was able to get the lower voltage settings for both wires within the specified range, but the full throttle voltages were just a touch high for both wires. I couldnt get those settings down because the TPS was maxed out for rotational movement. Any thoughts on this?

thanks,
chuck

 

The closed setting for the TPS is all you really need to worry about. Just as long as full throttle isn't a full 5v, you're fine.

Dale

 

overheating problem continues.
I drained the cooling system and installed a new thermostat yesterday after work. The coolant Im using is Sierra. Never used this type of anti-freeze before, but it was recommended as an interim product to use until my order of Evans coolant arrives. It is compatible with the Evans if any trace amounts are still in the cooling system when I do my switch-over. Since water is not compatible with the Evans coolant, it was suggested that I use this product 100% undiluted.

Even after draining the cooling system and changing the t-stat, the temps again went very high (approaching 230F) and that is with the cooling fans running at high setting from the moment I started the engine. This time the temps came up more slowly with no rapid jump after the 200F mark. I didnt get a chance for several starts to burp the system. The coolant that I drained out was clean and free of particlulate matter. The radiator is a relatively new Ron Davis all aluminum model with more capacity than stock. All the cooling system hoses are new. Why the over-heating on a rebuild with less that 1 hour running time?

Does anybody know whether this type of coolant is ineffective if used 100% undiluted or can cause overheating problems when used this way?

Still have running / idling issues after installing the new intake air thermo-sensor. This could be because adjustments need to be made which I didnt have time to do. Also didnt get a chance to pull any error codes. Tonight! In the meantime, any and all input appreciated.

chuck

 

Help!!! I am at my wits end regarding the overheat problem. If I can resolve this issue, then I can take care of the other issues and tuning. Cant run the engine more than a few minutes at a time until it overheats. Just to review:
-new rebuilt engine less than half hour running time
-all new cooling system hoses
-water pump is 1.5 years new
-new thermostat
-radiator is Ron Davis all aluminum at 1.5 years new
-cooling fans can be turned on with a switch and at high with a/c on

I picked up some block test liquid from NAPA which tests for the presence of exhaust in the coolant. The way it works is to pull air out of the top of thermostat housing which is sucked though the test liquid. If the test liquid turns from blue to yellow then there is exhaust in the coolant indicating a bad seal (on a piston engine a bad head gasket). If you get a little coolant in the test liquid it turns yellow and contamiinates the test. On my engine, it doesnt appear to have exhaust in the coolant.

I believe that the only option that is left for what could be wrong with my cooling system is an obstruction or clog somewhere as I have checked everything else.

Does anyone know of a diagram showing the path of coolant as it moves through the cooling system?

For those that have rebuilt an engine, is there anyway that a cooling port could be blocked when performing a rebuild?

Can the engine running extremely rich cause overheating problems?

Thanks,
chuck

 

http://www.autosportracetech.com/RX-7/coolingsystem.htm
Hope this helps.

 

Thanks Jim

 

Cooling issue resolved. Heres a copy of message I sent to Rynberg. Thank you Tyler. They say there is genius in simplicity. We so often overlook the simplest things and Tyler called this one.
================
Re: new rebuild overheat
--------------------------------------------------------------------------------
Chuck,

Yeah, I looked over your thread and am at a bit of a loss myself. I don't know anything about that Sierra coolant, but I doubt that could be solely to blame. It certainly does seem like the coolant isn't circulating somehow. Running with excessively retarded timing can make the motor run extremely hot. I would wait until you get the thermosensor installed before trying to troubleshoot anymore. Is it possible your aftermarket gauge is reading incorrectly?
Sorry I can't be of help....
-Tyler

Quote:
Originally Posted by a3dcadman
Rynberg,
Over the last couple of years reading your posts, it is apparent you know your stuff when it comes to the 3rd gen. Ive had my thread up for a while and havent seen any input from you so Im soliciting your help for any feedback you may have regarding my cooling issues.

https://www.rx7club.com/showthread.php?t=537034

Thanks,
chuck

The aftermarket temp gauge I bought 2 years ago which has been sitting on the shelf waiting to go back into my rebuild after 6 months is reading 60 degrees high (250 F when its actually 190 F). Ive had more than a few parts that worked before the rebuild just fine and upon reinstalling they wind up faulty?? Anybody else experienced that?

chuck

 

Glad it worked out....and it was relatively inexpensive.

 

Finally after 7 months, I got to drive my 7 again! Drove it around the neighborhood for a while and then got bold and drove it to where I work in Redmond and back - about 70 miles round trip.

On the return home, it was starting to get dark so I turned on the lights. Had the cooling fans running and the a/c switch was on to keep fans at high setting. Cabin fan was also on. Within 5 minutes of turning on the headlights, the oil pressure light comes on, the low coolant level light comes on, the charging light comes on, the abs light comes on, the exhaust overheat light comes on and the lights begin to dim. Since they all came on at once and the engine was still running just fine, and there was no visible evidence of any malfunction, I concluded that it must some kind of wiring / electrical glitch. My battery was now providing the juice for the electrical system and my new 180amp alternator had stopped working. Got the car in my driveway and the battery died completely.

Alternator stopped working because the 200amp breaker popped? Why, I dont know. So this opens yet another function that must be analyzed and resolved.

I am so relieved not having to pull the engine again because of bad seals or a internal clog causing overheating. That would have really sucked.

There are still issues with regard to idle surging, lack of power, running very rich etc. There are no error codes from the ECU. I tested a couple of other sensors to check the ohm load spec and they did not comply to oem standard. Not sure why no error codes were generated. Definitely needs some more fine tuning. But the engine seems to stabilize when under a light load. Seems that any inclines or hills I encountered were a little laborous because of a lack of power.

Theres plenty of info on idle, surging, rich running etc to help me get through those maladies so no need to elaborate .

Any thoughts on the 200amp breaker popping?

thanks everybody for the help.

chuck

ps - one thing I did notice after driving the car for a while - it seemed to smooth out a little the more I drove, from the first time I started it to the almost 80 miles I put on it this evening. I LIKE IT!

 

Almost 300 miles on my rebuild and it seems to run a little better and smoother every day and with a little more power. Sounds different though, almost muffled, restricted. Wondering if I fried the stock cat with all the rich red hot running prior to the rebuild, while I was trying to determine what was wrong with my engine.

Latest update on my charging problem. Simple once again. I had a 180 amp alternator built for me. Had not been used until I installed it the other day. Turns out it is defective. So it is going back to the company I got it from and they will be repairing it.

Another problem I had was no stock temp gauge temp reading. Fixed by installing a new temp sending unit. The small sensor next to the oil pressure sensor.

Unresolved issues:
1. surging high idle and extreme rich running, took out 40% fuel to stop sputtering. but still surging. possibly caused by new supra tt fuel pump.

2. absolutely no boost. gauge shows vacuum but no boost.

3. engine is generally gutless as compared to before, need tuning for sure. clogged cat problem? if the cat is the problem it will be resolved next week as Im building a metal substrate/magnaflow catalytic converter and should be able to install that next week

thanks for everybodies feedback.
chuck