NA Help Wanted
 

So, the time has come to ask for assistance.

A little background first: about 2 years ago I took my car back to NA. I had a local mechanic build the engine after blowing it up within a few months of going the FI way but I got tired of the engine running constantly too hot for my taste. I've read a lot of your comments regarding the correct temps in our cars and even though most of you insist that 220 degrees is not too much, I never felt confident with it.

Since trying to go back to the original NA settings in the car, I haven't had the chance to enjoy using my car for more than 30 minutes without it stalling and stopping on the spot until it cools down and it can be restarted again.

I figure this has to do with the MAF sensor but I have no clue if that is the case. I've tried 3 different OEM ECUs and none has worked properly. My car uses too much fuel with one of the ECUs and only 1 of them works half way decently.

I want to get the engine working properly for at least 6 months while staying NA and if I can get to enjoy the car, I'll consider going back to the turbo. I kept most of the parts I would need to do so.

I'd like to get some advice on what would be my best course of action in this matter.

Thanks,

Rafa

I'm trying to upload a couple of pics of my engine bay from my computer but I get an error message.

Any suggestions?

You are using a MS2?

No. I'm honestly considering buying one to see if I can fix all my issues. I already exchanged some pms with Reverant about it.

Is there any way I can find out if my problems are related to the MAF?

So you are using the stock ecu and it is doing this?

Do you have stock ignition coils?

if your car is overheating, it is unlikely that the MAF sensor is the culprit. You should be look at your radiator, radiator cap, coolant hoses, water pump, etc.

If the car is dying after warming up or extended periods of running (but not overheating), its likely your ignition coils are the culprit.

That's where I was headed. OEM ECU doesn't play well with other coils because dwell cannot be adjusted.

Sometimes when coils go bad they fail every time they get hot.

Interesting. The thing is: English is my second language plus, old mt.net members know that I'm mechanically challenged.

I don't think I can say the car is overheating. What it does is: the coolant temp goes up to 220 degrees and when the 2 fans come in it goes down again to about 190 but for some reason I can't understand the car will die after using it for 20 minutes in normal traffic. if I let it rest for 15 minutes, it restarts and I can get back home. I have a big, performance radiator and I've changed the radiator cap twice, I don't lose any coolant because every time I check the car before using it in the morning I find the coolant topped.

I'm very curious about your comment on the ignition coils. When I had the turbo, I was using COPs and they were working beautifully. When I took my car back to NA I reverted to the car's ignition coil.

Is there any way I can verify what you and shooter are saying about my ignition coils?

Would I gain anything by installing an MSII as I'm planning to do?

Thanks a lot for the help both to you and to shooter.

Rafa

WOW shooter!

Loved your tee shirts :bowrofl::bowrofl::bowrofl::bowrofl::bowrofl::bowr ofl:

Even I understand them hahaha:giggle:

If you go back to the MS2 and COPS then you can eliminate the coils as a possible problem. You can also adjust the temps where the fans turn on and off.

But some detailed pictures of various areas under the hood could maybe give us more clues. Left side of engine, right side of engine, front of engine, back of radiator, front of radiator, back of engine...with good lighting and focus, and not from 6 feet high when the engine is at your knees like the noobs do it, haha! We need close enough to see details.

That was precisely what I was trying to do but for some reason, mt.net doesn't allow me to upload pics from my computer and neither I'm I receiving emails for this subscribed thread. Weird.

I like the idea of going back to COPs and the MSII.

BTW, I sent a link of your tee shirts to 2 of my sons.

get a can of compressed air. run the car till it dies, shoot the compressed air at the coils until they cool. (obviously don't freeze them or anything). Try to start the car.

if it starts: its the coils. If it doesn't start, then you either did it wrong or the problem is somewhere else.

Or follow Steve's advice and run the MS2 + COPs.

Got it. I'll try this and get back to you.

Thanks,

Rafa

So, back again with additional questions.

My car has been at the shop for the last week and a half. We've changed everything we could think of.

Here's a list of things done:

1) installed a thermostat (I was using it without a thermostat).
2) Changed the water pump.

I don't have any issues with coolant temps any more. Top temps are 210 degrees and then the fans come in and temps go down to 185.

But the thing is; when we drive the car on errands for say more than 20 minutes, it feels like it runs out of gasoline, it starts backfiring and it dies. We sprayed the air compressor on the coils even though they did not feel like they were excessively hot but nothing happened. If we leave the car alone for 10 minutes it will restart but a short time later it will stop again.

We changed the fuel pump and the same thing keeps happening.

Is there any other sensor temp related that could be doing this?

Thanks,

Rafa

Sounds similar to the problems i had with my wife's piece of shit saturn. It would die (within 50 yards) at the exact same spot, provided we were going the same route. Ended up being a crank position sensor that failed when it got to a certain temp. It would start back up and be fine after the first stall.

Thanks man. I'll check the crank position sensor.

check the fuel filter?

yeah we did; we put in a new one. It's really weird. We even changed ECUs and it keeps on doing the same thing.

I also checked with my mechanic about the CAS and he said he thought it was not that because he figures the car would not even start if that was the issue.

Also, the car runs fine if you're on an open road but it only does this while stuck in regular daily traffic.

We're at a loss.

Electronics can do random things when failing due to heat. I threw parts at the saturn and nothing worked. I would have never thought to look at the cps, due to the symptoms. I figured it was a work/no work sensor. I got lucky with a phone call to a local saturn dealer, who pointed me in the right direction. He was just the parts guy but went above and beyond.

Have you changed out the coils?

Steve, I'm not discarding your suggestion. I'm trying to find out how I can check it out. I live overseas and it's not that easy for me to get a part like that one. I've been googling it to see what I find.

Thanks for the help.

I am not familiar with where the cas is located on an NA. Is it possible to add some heat resistant tape/foil/something to reduce the heat?

from m.net:


"STO962
Third gear

Join Date: Sep 2008
Location: TN
Posts: 751
Quote:
Originally Posted by Jim (Pop VII) C
Do not see a real practical test for the CAS. It is an optical sensor and has a rotating disc and light inside. If the voltages are correct does not mean it works.

The only practical way I see is to swap it out with another 1.6 unit.
If the voltages are correct, it has to work. The ECU is looking for a square wave signal from the two sensors and as long as it is seing that, it should work. Ideally, an oscilloscope is the best way to test it but a voltmeter will do in most cases.

I think I know what you mean though, as these can fail intermittently. The sensors can suffer from heat/temp induced failures. I have also seen the optical sensors have problems due to oil contamination from internal seal leakage. The oil will block the optical sensors. In this case it may check good while you're testing it but it will still have problems in operation. However, if the test is done correctly and it fails, you can pretty much bet on it being a bad part.

Thanks hsue for clarifying the wire colors for each signal. You're also right about the optical and the magnetic (Hall Effect) sensor being electrically identical as far as testing. They both switch the 5 Volt signal on and off, they just go about it in different ways. The same test works for all NA models.

Back probing the connector is the tricky part for getting an accurate test. I have much better results using test leads with a "bed-of-nails" type alligator clip."



I'll try this tomorrow.

Everyone keeps saying coils. Did I miss when you checked spark when it was disabled on the side of the road? My guess is your CAS and coils are working fine, you need a new temp sensor in the back of the head, or the wiring to it has failed.

This happened to an old truck I had, and when they fail they often read -40 degrees, and the ECU gives it an inappropriate amount of fuel.

Thanks curly.

Us old guys have to help one another :giggle:

I'll check it tomorrow and if it's not working properly, I'll get a new temp sensor tomorrow.

Just bring some plugs with you for a drive. As soon as it stops, plug them into the wires and crank to check for spark. If they fire I bet it's fueling related, because of a temp sensor. Or if you have a wideband, I bet it's going full lean.

I'm still guessing the coils or a sensor are failing when they get enough heat in them.

Coils and magnetic sensors have many windings of small diameter wire in them and when they heat up, they expand slightly. If there is a break in a wire in the windings it may work well when cold but upon expansion due to heat it may grow enough to pull the broken wires apart causing failure.

Similar things can occur with printed circuit boards on rare occasion.

I hope this is at least useful information to you, my friend.

So, we decided the issue was fuel related and decided to concentrate exclusively on that.

We think (emphasis on "think") that we may have found the culprit in the TPS. We tested the car with a borrowed one and it worked flawlessly. I'm lucky that some time ago I bought another throttle body from an mt.net member and we're about to test the car with that one.

I'll post the final results.

Many thanks to all who assisted.

Rafa

Back again.

I'm driving the car back from the shop. No cooling issues whatsoever.

The only issue left has to do with fueling. My mechanic could only avoid the problems with the car stalling by combining the new TPS with a 255 Walbro fuel pump. At low RPMs the car will basically use fuel like a V10 engine and the engine is overwhelmed by so much fuel. It sputters quite frequently and the car bucks; from 3,500 RPM on when the car is working at the correct temperature, the engine is perfect.

I'm seriously considering purchasing an MS3 from Reverant and working out those kinks that way.

Do I have any other options to try with the OEM ECU in the meantime?

Thanks,

Rafa

So what your mechanic has done is overwhelm the stock fuel pressure regulator and the injectors, to increase the FPR's psi, and the injector's flow rate.

I'd suggest putting in a 190, since the 255 overwhelms even a proper working fuel system. Then send some 99 injectors out to RC engineering, as they only flow a little bit more than stock so the OEM computer will handle them, and will be a great upgrade for when you install a MegaSquirt. Then check the resistance values of your coolant sensor and replace if needed, and test fuel pressures of the FPR. If all of these are old, they're fairly cheap, so you could also just ditch the tests and replace them.

I've had one NA that stumped me completely, it would refuse to start well when cold. Never tried a new temp sensor, I ended up putting a small worm clamp on the return line. This increase fuel pressure and gave it enough fuel to start properly.

Thanks curly. These options sound like a solid plan. I'll try the worm clamp on the return line first while I wait for the 190 fuel pump to get here.

Local mechanics are generally good for regular engine maintenance routines but not for much else. He even told me my Miata didn't have a FPR. :giggle:

Yeah, get your Miata out of there.

Don't do the worm clamp with the 255, it'll just make things worse at idle by increasing the fuel pressure. It's a trick for a stock pump.

Hey Rafa! I hope you are doing well, long time no talk!

I read your post, as mentioned next time it dies, pull over and hook a spark plug and wire up and see if you are getting spark. also, look at the tach too. If you spin the motor over, it should spin around 300 RPM on the starter motor, and your tachometer will show this.

IF the CAS if failing, when it dies on you, the tach will not show any RPM as it won't know the engine is spinning over, and of course no spark since it doesn't know the engine is turning.

If it's a coil, tachometer will show RPM on the starter, but no spark. If it ran on 2 cylinders when this happened, it could be a coil as the car will run on 2 cylinders if one coil fails.

Thus if it's ignition related, I'd say 95% chance it's the CAS, and yes they can fail only when hot, but work fine when cold.

Regarding fuel pressure, you could hook up a fuel pressure gauge in the car, they are not expensive. Then you could check the pressure at any time and KNOW what it is and if it's not right.

I'll try to buy the OEM fuel pump locally then and try it. It's harder to source the 190 Walbro and the 99 injectors locally than the stock fuel pump.

One last question: would you suggest the worm clamp in the return line with it?

Thanks

Hey Pat; long time no speak. I see your car is up in jackstands too. Sorry to see that.

I'm pissed with mine. hehehe.

Yeah mine is for sure! I'm hoping to have it running by May 1st. I'm making good progress but everyday there's a few little things I can never predict that pop up that take up time and I don't get everything done that I wanted to.

If you need anything from US I'll send it to you as a gift, just let me know.

Thank you Pat.

So, I decided to keep on using this thread to get assistance for my engine's ongoing issues.

The cooling is finally fixed and working properly so now I want to address my fueling issues.

Following a suggestion made by shooter in another thread, I ordered a DW100 fuel pump (equivalent to 165 psi) and finally got it last week. I took out the Walbro 255 that was in my car and replaced it with the DW one. The fueling is better but it still not working properly.

I decided to buy an MS2 that was up for sale on m.net. I will receive it by the end of April. In the meantime, I wanted to know 2 things:

1) besides an IAT sensor and a wideband o2 sensor, what else do I need to install the MS2?

2) is there anything else I can do in the meantime with the OEM ECU to improve my car's fueling issues?

The IAC valve won't compensate when I use the AC and the engine bogs down and backfires once in a while. It seems like this happens when I try to floor the car. These symptoms improve when the engine is working at the correct operating temp but they don't go away all together.

Thanks,

Rafa

That's weird. I wonder if the mechanic did something funky to it?

I'd address these issues before installing the MS. There's something wrong with the engine and it's probably not the ECU. Adding th MS will just add new problems and lack a tuned map.

There have been some good diagnostic tests suggested that'd I'd follow through on before putting hose clamps and ecus in the car hoping one makes the problem go away.

The thing is, I've had the compression tested, checked the oil and everything is fine.

It's also weird because the engine will start working perfectly and respond to acceleration normally; but it's not consistent. When I start to accelerate the car from standing still at a light, sometimnes it bogs down. When that happens, I press the clutch, accelerate and it catches back on. I also have to admit that when I use the AC, the car doesn't want to pull and it feels like I lose a lot of horsepower.

One reason I bought the MS is that I plan to go back to COPs. When I had them on, the engine would work properly.

I got a prior suggestion about the car's coil packs but I didn't find any locally so I decided I might as well get the MS and proceed with the installation. At least, that way I'll be able to verify some parameters that I can't verify now.

Thanks for the help,

Rafa