aseychell

Have a strange issue with my 350TPI. Engine has been recently overhauled with new rings, cleaned valve seatings, new head gaskets, etc...

I do not use the car often and this is probably the 4th time since I have taken it out for a ride. As I have removed the stock exhaust manifolds and installed aftermarket headers, I had to re-program a chip modified to activate the EGR at very high temps.

Car ran fine however yesterday while driving I noticed that it didnt want to accelerate past a certain rev. Today I went to check the plugs and was happy to see a perfect burn (light brownish) on all of them. I tried to rev it up in my garage and noticed that at exactly 3000 RPM, my rev counter drops to 500 (digital dash) and the car starts sputtering. Feels like a rev limiter but it surely isnt. Non SES lights whatsoever I am sure the SES worked as I previously had a problem with the MAF which was throwing code 34. Also the SES lights up before starting.

I will try to find some time to remove the chip and revert it to factory but perhaps anyone of you guys encountered this issue? It is very strange to me that the Rev counter drops to 500 when this happens. Any clue from where the rev counter signal is calculated?

Vader

Loss of power at higher RPM can be a sign of incorrect valve timing.

aseychell

I would agree with this however the car was working fine a few weeks ago and all it did between then and now was just sit in a garage.
Also incorrect valve timing wouldn't cause the tach to go to 500 as soon as it hits the 3K. To be honest I am suspecting a bad ignition module. I noticed that past 2500 the dash lights dim a bit and then at 3000 the rev counter drops to 500 and the engine starts sputtering. I am assuming that the tacho signal is taken from the ignition module not the ECU. Might be wrong though here.

Vader

Yes, the tach signal is directly from the HEI amplifier module. It might be a good idea to check the power wiring to the coil and ignition system. A marginal connection may be resistive enough to drop voltage at higher loads. A voltage measurement at the distributor might verify this.

aseychell

Hi Vader. Thanks for your help.
What do you mean exactly by 'voltage measurement at the distributor'? Are there any particular pinouts I should probe on the HEI?

Vader

Monitor the voltage to the distributor pink/black wire while the engine is running. If the voltage drops to below system voltage (about 14V) when RPM is increased, there might be a resistive connection in the power circuit. Grounds are also important.

aseychell

Hi Vader

I checked the voltage on the thick pink wire going to the coil beside the distributor. I have 14.1V during idle and when it hits 3000 it drops maybe to 13.8V so I think that should be good.
I hope it is the right pink wire as I couldn't see the black stripe on it. It goes to one of the top connectors on the coil then there is another thinner pink wire on the other coil connector going to the amplifier in the base of the distributor.
Is it the correct wire I tapped?

Vader

That voltage should be sufficient.

Are the cap and rotor intact? Spark scatter from a failing rotor might be arcing to the lower voltage wiring, affecting the tach reading.

Is the pickup coil in good condition? These can suffer from corrosion and insulation breakdown.

What year GTA? Some had a tach filter in or next to the distributor.

aseychell

This is a late 87. Cap and rotor look fine. I tried looking for arching in pitch dark and can't see anything. High tension leads all new MSD. the plate under the rotor is a bit rusty TBH but isn't this a hall effect system? Don't think it matters so much. With regards to the actual rotor you think it would cause the digital tach to go down EXACTLY at 3000 everytime? It really feels the same a rev limiter but today I also double checked the map and the rev limiter is set wayyy to high at 10k.

aseychell

Some small update.
So I hooked up my laptop with TunerPro RT and noticed I had SES on. Error was MAF Low. This error happens every once in a while and a simple switch off and on of the engine makes SES go off. Did the same this time. Believe me I went through all the MAF wiring and relays and all are working fine. Even the MAF works as I can get a good reading on TunerPro. Putting this aside...
I revved the engine past 3000 and strangely enough, on my laptop I could see 4700 for sure. Tach still did the same dropping to 500 as soon as it hits 3000.

So I said lets go for a short spin and get a log. Although I could not see the tach going down at 3000, the car feels like it doesnt have enough power to go past it either. Strange thing that in park, tach goes down to 500 @ 3000 while the ECM still gets the proper rev count. However as I said, even though in park the ECM is showing 4700, while driving the engine cannot go past 3000. Looks like the tach is suffering the problem in park at the same spot that the engine loses power while driving (not sure I am making sense here...)

Attaching the log maybe someone might get some insight from it? Please rename to .xdl as forum blocks these.

aseychell

Another very promising update.....

So in view of the loss I was at I started a process of elimination. The luck is that the issue is not intermittent and I can easily detect it as the tach drops always at 3000 while in park & neutral.
So...
1. Removed the chip that I had programmed reverting the car to stock. Check engine came on due to egr. Car behaved exactly the same. For now leaving it with stock chip.
2. As I always have doubts on MAF as occasionally I get MAF low error, I disconnected MAF cable. I said if it is the MAF, I should at least experience the problem at another RPM figure not exactly at 3000. Car still behaved exactly the same. All it changed was some backfiring due to lack of MAF input. Plugged back the MAF connector.
3. Suspecting again electrical problems related to ICM as this is where the tach gets it's signal I decided to try disconnecting the EST cable (the one we use for base timing)... Voila car runs fine. Can easily exceed 3000. The dash lights don't dim before car reaches 3000.

Now I know it's not a solution. I am hoping someone can help me out on this last bit. Why is the car running erratic when the ECM controls timing? Could it be the ICM has a fault in the circuit where it receives signals from the ECM? Can an ICM go faulty in this way. Feels like the ICM is shorting something past 3000.

aseychell

Would appreciate some input here guys. Today I changed the ICM (the module in the distributor) and while I was at it I also cleaned the Distributor cap points and changed the rotor arm.
I am still without any chip. Stock ECM. Check engine didnt even come on. Still the same!!! Tacho drops down to 500 as soon as it hits 3000.

Any clues please? Why is the ECM cutting exactly at 3000? Could it be the module attached to the bulkhead? What is its use exactly?

aseychell

Tried to check the TPS today. 0.54V at rest. Goes up smoothly till 4.3V at WOT. So that's also ruled out. Am planning another datalog session tomorrow and will inspect sensor reading.
What I noticed today while using WinALDL is that the spark table, the box moves only within the first column. Looks like the MAF values are remaining in the range of the first column.
Any ideas guys?

aseychell

I really need some tips here as I have been going around this issue and cant drive the car as it is.

Still have the issue of stuttering when I am driving in the regions of 3000 RPM.

The obvious first thing I did is pull error codes. This time to eliminate possibility of software definition files and mis-interpretation of codes, I decided to use the good old paper clip method.

- Got Codes 32 and 34.

- As I had removed the AIR system and the EGR solenoid was not convincing, I decided to program a PROM with maximum MAT to enable EGR.

- This solved Code 32 but I still have Code 34. This error means MAF reading low gm/s. Here starts the long process of trying to figure out the cause to no avail. Needless to say, I disconnected the battery for around 5 minutes between every test.

- Checked with tunerpro that I have MAF readings. They were correct measuring 100 at circa 2600RPM.
- Verified that both the MAF and Burn-off relays work fine and also traced all the cabling/connectors between the ECM, Relays and MAF
- Checked TPS both from tunerpro and backprobing with a multimeter. 0.54V idle.
- Checked the rubber pipes before and after the MAF. No holes or damages. Car has stock airbox.
- Blocked the PCV pipes (both the driver and passenger side going to the Throttle body and intake manifold respectively)
- Blocked the vacuum pipe going to the EGR solenoid
- Blocked the vacuum pipe going to the cruise control vacuum ball and the heater controls
- Disconnected the signal to the rev counter as I was also suspecting a short in the digital dash tach module

At this point I am assuming it is not related to vacuum leaks although I have ordered and EGR blockoff plate to be 100%. Dont think this will make a difference though.
So I started looking at other parts based on suggestions I read from the TGO. Quite vast but....
- Changed the Ignition module (the one mounted in the distributor assembly) with a new one
- Changed the ECM with a known good one
- Changed the MAF sensor as mine was descreened. The MAF isnt new but it was pulled off from a working car and I also get proper MAF readings with this one
- Changed the TPS with a known good one and re-calibrated
- Checked Fuel Pressure getting 38psi even when revving the engine. To be sure I disconnected the fuel pressure regulator vacuum and started getting around 48psi
- Checked Injector resistance. All of them are at 16.5 - 16.8 Ohms

Also worth mentioning that if I disconnect the jumper for the base timing (tan wire), Code 34 is still there but the car doesn't exhibit the issue with stuttering. I only get some backfires which is probably normal due to static timing.

I honestly feel I cannot try anything more than this. As I said, I dont think the block off plate is going to do any miracles here although will still give it a try when it arrives. I also intend to block off the other inlet port going to the charcoal canister and report back as it is the only inlet to the TB that I still didn't touch.

Is it possible that both MAFs are faulty? When they go faulty, will they still give out a reading of airflow?

Could really use some help here.... I am ready to do datalogging and send over if they can be of any help.

GeneralDisorder

iTrader: (1)

If you want to check the MAF, you need to record the grams/sec at WOT and RPM, and then put those numbers into a VE calculator.

Try driving it with the MAF unplugged?

Other possibilities - plugged exhaust comes to mind.

GD

KyleF

This is a good one. Plugged exhaust as GD mentioned is an interesting one. Do you still have a Catalytic converter? Are the pipes in front of it getting red? I did have this happen on a 5.0 Mustang, it didn't exhibit your exact issues, but it sure choked all the power out of the car. After running for about 5 miles, the pipes would be Red. Didn't affect timing or gage function.

To me, the odd issue is the behavior of the tach versus what the ECM is seeing. I would suggest you need to see the fuel pressure at the magical 3000RPM mark, but being that this happens under load and in park both I wouldn't think fuel delivery is you issue, but might want to check it anyway.

Just to confirm though, you see 3000RPMs on the tach, but in Tuner Pro RT or WINALDL you see that the ECM is reading 4700? What is you RPM fuel cut off set at in your chip? That is kind of a low RPM, but something worth checking. I still don't see why that would affect the tach reading.

When you are looking at your RPM in the ECM... starting from idle and rev it up. Does it go up smoothly in the ECM or jump around? Does it match it or is it off by a progressive amount. As in... at 750 on the tach, is that what you see in the ECM? Same question at 1500, 2000,2500... or does the tach hit 3000 and drop while the ECM keeps climbing to 4700? Are you doing the rev quick or slow?

Have you checked for issues with you timing chain yet? You can check for play by watching the rotor while you rotate the crank on the hub bolt (In N obviously). How many degrees does the crank turn before the rotor moves? Then turn back the other way and ask the same question. This doesn't isolate the timing chain, but does give you an idea of the stretch in the chain and backlash in the distributor gear. I haven't done it, but my understanding is the distributor may need to be shimmed to take up some of the backlash between it's drivegear and the cam gear

This is a very interesting issue. I will follow along and chime in as I can. I can't help feel with the relationship between ESC/ECM/Tach that you don't have some sort of electrical interference or poor grounding issue in the ignition system or for the ECM.

aseychell

Thanks both for you replies. I am quite desperate ATM.

So to answer the exhaust question, I have Edelbrock shorties and a magnaflow exhaust with only the rear muffler. No cats so I would exclude an exhaust clogged issue. Also no red hot pipes.

Re fuel cutoff I will check and revert back but it is the same as stock bin. Didn't touch that.

Revs on tunerpro and the tach match and they climb up steady both when accelerating slowly and quickly. That is until it hits the 3000 regions when the tach goes down to the bottom and tunerpro continues climbing. Could it be that due to SES the ECM is in limp home mode and RPM are limited in this mode? My daily driver does a similar behavior.
Note that while driving the tach doesn't drop but it's very difficult to go past this rpm due to power loss.

Re timing chain, well it is a brand new one including the sprockets. It's a Cloyes kit the one that has dual chains. Have to check about the slack though so will revert back.

Do you think if it was a timing chain issue, disconnecting the tan jumper would sort of fix the issue though? And would code 34 be relevant in this case?

KyleF

I can appreciate that, we have all been there a time or two


Understood, just trying to conceive anything that could exhibit such behavior. It wouldn't explain other items you are describing. However, while we are talking about the .bin. Is there any possibility that the file got corrupted and as you have made updates it has just carried that corruption along the way. I know you said you went back to stock, but do you have more than one copy of your stock .bin? How about the chip itself, can you upload your .bin on another chip and use it to eliminate the chip being an issue? Again, I don't think it explains all your symptoms, but they may not all be the result of the same issue. Just tossing some things to check out there.

Thanks for the clarification, but it honestly made things more confusing. Not more confusing in understanding your situation, just a more confusing diagnostics puzzle. It just seems as something is holding it back. Fuel Cut, Ignition cut out, or the ECM. Is it just plainly possible the distributor is bad???

You probably don't have issues in the chain then, but it never hurts to check. The issue may be in the cam gear/distributor gear mesh. The test I mentioned would show both. If you are confident in your chain, it would point to the gear mesh. The distributor may be moving up and down on the cam gear slightly or the teeth on the gear may have worn and causing timing to jump back and forth by a few degrees. Still hard to explain why this would cause all of your symptoms.

I am not sold that the Code 34 and your failure to get passed 3000RPMs are necessarily tied together, I am not sold that they are not. Again, I am not sure any of my suggestions are the magic sauce to fix your issues, just tossing things out to investigate that may cause some of the symptoms.

Just noticed this as I was reading back... did you get a code 42 while disconnected? If not you should have.

aseychell

Hi guys,
So today I made some good progress. Although it opened up others.... Here it goes:
- Tried to plug the charcoal canister port as the last potential for vacuum leaks - Nothing. Still Code 34.
- Decided to check AGAIN the GNDs, Supply and Signal at the MAF directly with a multimeter.
>I had 12V on the Red wire during fuel pump priming and/or engine running (supplied through oil press switch)
>I had proper Grounds on the Black and Black white wires
>I also saw voltage swing between 1V to 5V while air flow changed.
As I was backprobing, while I was removing the wire pincher all of a sudden the engine switched off!!! Started again and starting wiggling the MAF connector and it did it again and again. I started bending the glands of each of the 5x pins in the MAF connector with a thin needle to ensure a solid contact and finally cleaned with alcohol...Started engine and VOILA. SES if now off and wiggling the connector doesn't affect anything. I tried it numerous times and now I will test again tomorrow when the engine is cold to ensure that the Code 34 and SES problem is solved. I am almost 100% that this was the issue. All that effort just to find out a lose connection at the MAF... I hope this whole procedure helps others to solve Code 34.

But hey. Its never a dull day with these cars.

I was now hoping that the 3K RPM gauge issue and stuttering has now been solved also. Went to try it and noticed that at around 3K I still have the stuttering and the tach while in Neutral still drops down. At a certain point while I was trying again the 3000RPM while driving, the speedometer freaked out and now it reads 100 (without MPH) and at times it switches to 188 and mph. Sort of like when you turn on the key for the first time (digital segment test)

So yes, I solved the SES, I dont have any codes now BUT now I have a speedometer issue and engine still stutters at around 3K...

Tried TunerPro while driving and the vehicle speed is displayed properly so the trans speed sensor is working fine. Am now suspecting that the RPM issue is also related to a faulty dash which is not a nice thing. Are there people who know how to fix these 80s electronics around? I am a bit electronics literate but wouldn't know where to start or how to test the RPM and speedometer components. Will have to open another thread i the electronics section.

As KyleF mentioned above, it looks like the SES/Code 34, RPM falling to 0 and stuttering are not related and I have to tackle them separately.

BTW, Fuel cut off is at 10031RPM and yes I tried 3x different chips to ensure it wasn't a corruption issue. I also read them again, removed the empty fills at the start (due to larger memory) and loaded the bin again in tunerpro properly.

Any further ideas I should try re stuttering? Perhaps I will try to find a longer fuel pipe to extend the fuel pressure gauge to the windscreen and try it out to see what happens to the fuel while driving.

KyleF

Fun stuff, but at least you got one problem down.

Back to the RPM problem.. My understanding is in N or P you get the 3000 RPMs, tach drops, but engine still speeds up, and Tuner Pro displays what you would assume is proper RPM from the ECM. Though if driving, the engine doesn't have power to get above 3000RPM-ish range, tach drops, but you won't see higher RPMs in Tuner Pro because the engine is no longer accelerating? Is this correct? Additionally now you are saying you have issues with the MPH display?

How about that Code 42? When you disconnect the Tan ESC wire does it give you a Check Engine?

aseychell

Almost correct.... While driving, the tach never drops. It struggles to go past 3000 but eventually it does. Like the engine clears up and then continues climbing. The tach ONLY drops while in N or P.

And yes, now my speedometer is not working either. Looks to me like my digital dash needs some good refurb.

Re. Code 42, I didnt try it. Will check again tomorrow while I am back in the garage.

KyleF

Check for that Code 42... if you are not getting it, there is another clue something more than just the dash is wrong. I think with your symptoms you are dealing with an electrical issue that is not isolated to the dash, but I have never had an Electronic dash in a third gen.

aseychell

Will definitely do tomorrow (as now its 22:45 here and the neighbors wont like the noise...)

Thanks again for your help

aseychell

Continuing the mystery (or should I say misery...)

Tried removing the ignition jumper cable and ensured code 42 comes up fine. Cleared the code.

Than yesterday I went to check the car from a cold start to see the behavior of the SES. Guess what. It came back.
So I back probed again the Dark Green signal wire from the MAF to ensure the MAF is working and once I connected the multimeter and started again, no SES. Voltages on the signal cable start at 2.3V before starting/during priming and then at idle go down to 0.8V climbing up to 3V while revving up the engine.

Then I disconnected the multimeter and started again. No SES.

So I left the multimeter probe with the dark green cable and waited another day (today) so that I can see the voltage on the MAF signal cable from a cold start. Started the engine and I got no SES. Voltages were fine.
Needless to say, I now disconnected the probe and no SES yet. Will again check tomorrow without probes.

Also, yesterday and today, the speedometer on the dash is working fine again. (not the tach which still dives to 0 as soon as I hit 3000 in N or P)

The issue with engine stuttering around 3000 while driving is very intermittent. At times it does it, at times it keeps on climbing normally.
I even hooked the fuel pressure gauge while driving and it is always between 35 - 38 PSI even while the engine stutters.

It really feels like an electrical issue such as bad grounds or something but I did all tests to my knowledge to ensure I have good grounds from the battery negative to various locations on the body and engine block. Resistance is always in the regions of 0.8 Ohms max and I do not have any residual voltage between the negative and body parts....

One question. Can it be a faulty ignition coil? The signal to the ECM goes from the pulser to the ICM while the signal to the instrument cluster is directly from the coil. So the ECM reading using tunerpro is actually the output of the pulser + ICM.
Would a fault coil perhaps provide a dirty square wave with excessively high amplitude causing the tach to freak out and affecting also the other instrument cluster components such as the speedometer? Am I making any sense? Unfortunately will have to order an ignition coil as I dont have any spare one but would like your opinion maybe what I am saying is completely not possible?

ploegi

Is it just a bad connection at the coil for the Tach?? So far as I know, that's the only thing fed off that particular wire...... have you tested coil resistance hot/cold?

aseychell

I changed the coil connector a few weeks ago as one of the tabs was broken. It was behaving the same before and didn't change anything. Have also checked coil resistance and unfortunately all was good......

No one ever had an intermittent coil failure?

ploegi

Not that we are willing to talk about........

Did you test the coil when hot as well? Running any kind of aftermarket ignition box? (MSD, Jacoobs, etc?)

aseychell

No TBH I tested it when cold. No ignition box either. Just standard system.

ploegi

Does the problem present itself immediately? Or does the engine need to be running for a while first??

aseychell

The issue with the tach dropping to 0 past 3000 happens always while in N and P. Stuttering is intermittent let's say 70% of the time it does it.

aseychell

BTW ordered a coil and distributor cap. Will be here by next weekend. We'll see...

ploegi

Don't neglect the rotor.

aseychell

Changed that a few weeks ago 😀

GeneralDisorder

iTrader: (1)

Do you have the ability to read live data?

Also do you have access to a graphing meter or scope?

MAF testing can be tricky. One thing you can do is look at live data - BLM and INT at idle and at say 2500 RPM. A dirty MAF will often show a higher voltage (more airflow) at idle, and too low of a voltage (less airflow) at speed. This will cause rich BLM's at idle (less than 128), and lean BLM's at speed (greater than 128). This is due to contaminants on the hot wire increasing the surface area of the wire - this causes the sensor to lose heat faster at low airflow, but has an insulating effect at higher airflow. Makes for a very odd failure mode but it is seen regularly with analog hot-wire MAF sensors. (I deal with these and their odd proclivities quite often).

You can then perform a Volumetric Efficiency (VE) test. For this you simply record the maximum grams per second at the highest RPM you can achieve (must be at WOT) and then plug these numbers into a VE calculator such as:

http://atgtraining.com/atg-volumetri...cy-calculator/

If you have access to a graphing meter or scope, you can check the scope trace of the MAF voltage. A rapid WOT throttle snap from a stable idle should exhibit a very pronounced spike as air rushes in, and then drop down and steadily climb to about 4 volts.

Something like this:

GD

aseychell

Hi GD
Will check INT and INT with tunerpro tonight. Will also datalog the session to be able to verify what I am seeing. If I remember correctly BLM were always in the regions of 128 but I tried too much things to be sure now.

I also have access to an old school CRT scope and will also try what you are suggesting and revert back. FYI before I installed this latest MAF I tried to spray some isopropyl alcohol but I don't think I was able to reach the hot wire due to the screens. The previous descreened MAF was thoroughly cleaned though.

KyleF

When the car runs well, are you getting any strange vibrations from the engine around the magic 3000RPMs? As we all know Electrical components can be affected by vibration as well.

Is there any change in behavior between Open and Closed loop?

Sounds like you may have an issue in your connector to your MAF that was remedied when you probed it, but may work its way free again and bring the SES back.

I really don't think your Tach issues and MAF code are related. I would still be looking at them separately as well - but not 100% sure they are not related yet. Let us know how changing the coil goes.

That info from GD is good stuff.

aseychell

Will surely let you guys know how it goes but as I said parts will be here perhaps next weekend.
In the meantime, I will take readings of BLM and INT and will also use that calculator suggested by GD to see if the readings are either too low or too high.
Will also connect a signal generator to the tach signal instead of the coil and see if I see the same behavior in N and P. This would confirm if the instrument cluster is acting up or if the signal I am feeding is messy.

As I said will keep you posted perhaps this information can also be used by others going through the same pain.

aseychell

Just realized that my $32 doesnt have values for IAT so I cant input them in the VE Calculator. Is there any updated $32 definition file? Couldnt find anything.

GeneralDisorder

iTrader: (1)

At WOT you are going to have very little heating of the intake air, so for the IAT you can use ambient or if you want to be conservative, ambient + 20 degrees F or so. With my car fully warmed up I'm usually seeing about ambient +20F at my cone filter behind the pass. headlight. If you want more accurate you can easily toss a thermo-couple on your multi-meter (many meters come with one) and put it near the air filter. At WOT your IAT will essentially be what you read near the air filter from your thermo-couple.

And in any case $32 is going to be a MAT sensor which is subject to a LOT of heat soak because it's in the aluminium intake manifold on the bottom of the plenum. It won't be an accurate indicator of IAT at WOT if there is any heat in the intake manifold. It's also a slow response brass-enclosed temp sensor like you would see in a coolant jacket which means it changes temp very slowly. Not at all useful for the VE test.

GD

aseychell

OK so I went to do some datalog and then played back the session.
Got the below readings. Note that I am running 160 baud so refresh rate was quite slow but at least I can see Airflow increases with throttle. I accelerated gradually so I didn't see huge airflow figures.
RPM, Airflow, EST_VE (%), Theoretical Load (%)
1050, 11, 20.52, 19.83
975, 10, 19.13, 18.49
1700, 25, 27.43, 26.51
2300, 29, 23.52, 22.73
2700, 36, 24.87, 24.03
3025, 38, 23.43, 22.64

Attaching graph from a monitor I created on Tunerpro.

Although airflow increases, is it normal to have such a low number? Max TPS voltage during this session was 1.2V so aprox 35% throttle.
Note that I used Baro of 29inch and IAT of 30 Celsius (had 28 on my multimeter in the airbox).

What do you think? Looks like MAF is actually working. It never went down to 2.5g/sec which is what the ECU would see to give out Code 34 at startup.

aseychell

Just did another experiment. While doing the tests suggested by GD, I noticed that dash lights were quite unstable. I remember that I saw this behavior the first time when I changed the alternator to a powermaster chrome unit.
I know its not recommended but what the heck for a short time, I disconnected the +ve to the battery and the plug on top of the alternator and started again. Guess what.... The problem with rev counter dropping at 0 when it hits 3K on N and P vanished. Tried multiple times. Before it used to behave like that everytime (not intermittent).

As usual, Code 34 came up after first start but didn't come up during subsequent startups.

As now it is late, I will stop testing but tomorrow after a whole day with the engine not being used, I will also check if I get code 34 on cold start.

Does this alternator behavior make sense? The battery I have is a brand new Optima Red Top.

GeneralDisorder

iTrader: (1)

Powermaster alternator's are JUNK. Not real keen on Optima either. I have a couple tear-down threads on the Powerfister and ACDeltrash alternators in the Product Reviews sections of the forum. It wouldn't surprise me if AC ripple was to blame for your digital dash freaking out.

I have come to the unfortunate conclusion through teardowns and failure analysis that you can't buy a quality CS130 anymore. Mostly due to the trash Chinese components being used - they are the only one's currently available for this old alternator design. No one that I can find currently manufactures a quality voltage regulator assembly for the CS130.

Both DC Power Engineering, and Mechman make LS alternators with CS130 fitment (billet front covers with CS130 mounting). I highly recommend these options. And Odyssey batteries.

GD

aseychell

I still have the stock alternator which I will try tomorrow. As for the battery, the optima is the only one in terms of size that I could find locally with enough cranking power. Will let you know first start without alternator and the 3K symptom with the stock alternator tomorrow.

Thanks guys for the help. Who know it might also cure the stuttering !!!

aseychell

By any chance, does anyone have a good $32B which sends the ECU command for 8192 baud? Seems like the best kept secret. Havent been able to find any. Also the $32B that I am managing to find online contains very few values. IAT, Battery voltage are all missing. Can see them in 6E files but these are not compatible with my BIN.

GeneralDisorder

iTrader: (1)

Why not switch over to $6E? If the engine is stock it's really easy to do.

GD

aseychell

I will eventually switch. Just don't want to pick a lot of projects at the same time. I heard I can use an 89 bin as they were still using MAF and just modify some fan switches?

I was in the garage and tried a $6E datastream definition which works at 8192 and has much more information.

Managed to connect and get data but after a couple of minutes it disconnects. Tried removing the jumper to disconnect the 10k resistor but still the same. While I was connected I did notice a high IAT (213 Fahrenheit). Changed to another IAT but still the same reading. Any clue why such a high reading? Other readings such as rpm, airflow, TPS, coolant temp... were fine.

I am using red devil River cable.

GeneralDisorder

iTrader: (1)

I wouldn't suggest relying on any data from a $32B PROM when using a $6E definition file. That temp is probably meaningless - the definition file may be using the wrong address or conversion. Those two masks are not at all similar.

Yes you can simply use the 89 BIN. 89 is the only year for $6E - which is a MAF based 7165 ECM mask. You have to change some fan switches to properly operate the fan relay and then you also have to disable the cold start injection as it is no longer used with $6E.

$6E is the best MAF based mask to use. It has the most development work done in the open source community so it has the best definition files, etc.

GD

aseychell

Understood. I guess this will take priority then. Might also be the reason why the ECU is disconnecting?
Would I be abusing of your kindness if I were to ask you for a recommended bin broadcast code?
Would an AUJM be good? It's of an 89 iroc with 5.7 too and 3.27 ratio with auto trans. ( Like mine)
Or would ARAP be better as it is of a vette?

KyleF

That could do it. Once the car is running it runs off the alternator and the battery becomes a load. Will be interesting to see what comes of switching the alternator.

GeneralDisorder

iTrader: (1)

Yes - use AUJM - don't use ARAP as the vette had aluminium heads and has a very aggressive timing curve.

Unfortunately the ECU disconnecting is a hardware issue with the 7165 ECU. They all do that and it's super annoying. Not impossible to work around but I found it really annoying so I went to the EBL Flash II system and ditched the slow 7165 ECU and all it's proclivities.

GD