puzzigully

Here's the output from the ECM.

you can see at Rec# 221, i turn off the ignition and rpm drop to zero.

at Rec# 240 the ECM (Fuel pump) voltage goes to zero and the maf goes to 23 (pull up resistor?)

you can see the maf signal goes from 10's to 7/8's then to 23.

I saw the burn off happen, just the ECM didn't


Rec Num Frame Time Time Stamp FP Volts RPM AFGS Ign Volts
# HH:MM:SS Secs Volts RPM gm/Sec Volts
212 10:25:21 AM 26.874 11.8 775 9.9 11.7
213 10:25:21 AM 27.001 11.8 775 10 11.8
214 10:25:21 AM 27.129 11.8 775 10.1 11.8
215 10:25:21 AM 27.257 11.8 750 10 11.7
216 10:25:22 AM 27.385 11.8 775 9.9 11.7
217 10:25:22 AM 27.513 11.8 775 10 11.6
218 10:25:22 AM 27.641 11.8 775 9.9 11.6
219 10:25:22 AM 27.769 11.8 775 9.9 11.7
220 10:25:22 AM 27.897 11.8 775 10 11.5
221 10:25:22 AM 28.025 10.9 825 10 0
222 10:25:22 AM 28.153 10.9 0 8.3 0
223 10:25:22 AM 2 8.28 10.8 0 6.5 0
224 10:25:23 AM 28.408 10.3 0 4.9 0
225 10:25:23 AM 28.52 11.1 0 5.2 0
226 10:25:23 AM 28.632 11.2 0 6.8 0
227 10:25:23 AM 28.744 11.2 0 7.1 0
228 10:25:23 AM 28.872 11.2 0 7.1 0
229 10:25:23 AM 28.984 11.2 0 7.1 0
230 10:25:23 AM 29.096 11.2 0 6.2 0
231 10:25:23 AM 29.207 11.2 0 7.3 0
232 10:25:23 AM 29.319 11.2 0 7.3 0
233 10:25:24 AM 29.447 11.2 0 7.2 0
234 10:25:24 AM 29.559 11.2 0 7.3 0
235 10:25:24 AM 29.67 11.1 0 7.3 0
236 10:25:24 AM 29.782 11.1 0 7.1 0
237 10:25:24 AM 29.894 11.1 0 7 0
238 10:25:24 AM 30.005 11.1 0 7 0
239 10:25:24 AM 30.117 2.8 0 23 0
240 10:25:24 AM 30.245 0.1 0 23 0
241 10:25:24 AM 30.357 0 0 23 0
242 10:25:25 AM 30.469 0 0 23 0
243 10:25:25 AM 30.581 0 0 23 0
244 10:25:25 AM 30.692 0 0 23 0
245 10:25:25 AM 30.804 0 0 23 0
246 10:25:25 AM 30.916 0 0 23 0
247 10:25:25 AM 31.028 0 0 23 0
248 10:25:25 AM 31.14 0 0 23 0
249 10:25:25 AM 31.252 0 0 23 0
250 10:25:25 AM 31.364 0 0 23 0
251 10:25:26 AM 31.476 0 0 23 0
252 10:25:26 AM 31.603 0 0 23.9 0
253 10:25:26 AM 31.715 0 0 23 0
254 10:25:26 AM 31.827 0 0 23 0
255 10:25:26 AM 31.939 0 0 23 0
256 10:25:26 AM 32.05 0 0 23 0
257 10:25:26 AM 32.162 0 0 23 0
258 10:25:26 AM 32.274 0 0 23 0
259 10:25:27 AM 32.386 0 0 23 0
260 10:25:27 AM 32.498 0 0 23 0
261 10:25:27 AM 32.61 0 0 23 0
262 10:25:27 AM 32.722 0 0 23 0
263 10:25:27 AM 32.833 0 0 23 0
264 10:25:27 AM 32.945 0 0 23 0
265 10:25:27 AM 33.057 0 0 23 0
266 10:25:27 AM 33.169 0 0 23 0
267 10:25:27 AM 33.281 0 0 23.1 0
268 10:25:28 AM 33.393 0 0 23 0
269 10:25:28 AM 33.52 0 0 23 0
270 10:25:28 AM 33.632 0 0 23 0
271 10:25:28 AM 33.744 0 0 23 0
272 10:25:28 AM 33.856 0 0 23 0
273 10:25:28 AM 33.968 0 0 23 0
274 10:25:28 AM 34.08 0 0 23 0
275 10:25:28 AM 34.192 0 0 23 0
276 10:25:28 AM 34.303 0 0 23 0
277 10:25:29 AM 34.415 0 0 23 0
278 10:25:29 AM 34.527 0 0 23 0
279 10:25:29 AM 34.639 0 0 23 0
280 10:25:29 AM 34.751 0 0 23 0
281 10:25:29 AM 34.863 0 0 23 0
282 10:25:29 AM 34.974 0 0 23 0
283 10:25:29 AM 35.086 0 0 23 0
284 10:25:29 AM 35.198 0 0 23 0
285 10:25:29 AM 35.31 0 0 23 0
286 10:25:30 AM 35.422 0 0 23 0
287 10:25:30 AM 35.534 0 0 23.1 0
288 10:25:30 AM 35.646 0 0 23 0
289 10:25:30 AM 35.757 0 0 23 0
290 10:25:30 AM 35.869 0 0 23 0
291 10:25:30 AM 35.981 0 0 23 0
292 10:25:30 AM 36.093 0 0 23 0
293 10:25:30 AM 36.205 0 0 23 0
294 10:25:30 AM 36.317 0 0 23 0
295 10:25:31 AM 36.429 0 0 23 0
296 10:25:31 AM 36.54 0 0 23.1 0
297 10:25:31 AM 36.652 0 0 23 0
298 10:25:31 AM 36.764 0 0 23 0
299 10:25:31 AM 36.876 0 0 23 0
300 10:25:31 AM 36.988 0 0 23 0
301 10:25:31 AM 37.116 0 0 23 0
302 10:25:31 AM 37.227 0 0 23 0
303 10:25:31 AM 37.339 0 0 23 0
304 10:25:32 AM 37.451 0 0 23 0
305 10:25:32 AM 37.579 0 0 51 0
306 10:25:32 AM 37.691 0 0 23 0
307 10:25:32 AM 37.802 0 0 23 0
308 10:25:32 AM 37.914 0 0 23 0
309 10:25:32 AM 38.026 0 0 23 0
310 10:25:32 AM 38.138 0 0 23 0
311 10:25:32 AM 38.25 0 0 23 0
312 10:25:32 AM 38.362 0 0 23 0
313 10:25:33 AM 38.474 0 0 23 0
314 10:25:33 AM 38.585 0 0 23 0
315 10:25:33 AM 38.713 0 0 51 0
316 10:25:33 AM 38.825 0 0 23 0
317 10:25:33 AM 38.937 0 0 23 0
318 10:25:33 AM 39.049 0 0 23 0
319 10:25:33 AM 39.161 0 0 23 0


any ideas?

puzzigully

Sorry for the poor formatting....

As i entered it, it was formatted so it was all in column, but the board did something funky to it...

Happy to send to someone or if they have a way to pretty it up.

Cliff Harris

The forum automatically eliminates all extra spaces and converts all tabs to spaces. You can get around that by selecting the text and clicking on the "#" symbol. That will surround that part of your post as "code" and keep all the formatting. An example (1st without formatting and then with):

abc def ghi jkl

puzzigully

ok,

try again?

hope this helps you guys to help me

One thing that I didn't notice, but should have....
The alternator wasnt charging the battery.

I took it for a drive on the weekend as was left stranded as the battery was running everything!

Took me 8 hours to get home!

all the info is there, just gotta look.

AJ123

Cliff I gave up trying to solve this problem and took my Vet to a friends shop. He has repaired wires fixed my mess-up on a wire connection. We confirm that the burn off wire is working and seen it glow. The code 36 was off for a while. New burn off relay and relay plug. We both have gone through the 36 trouble check list code is back.

two questions John said he read that someone on this subject claimed that the prom had a fault that made this 36 code come up on certain vehicles. Any knowledge of this.
Second question when the Kessler transmission was installed and the Dakota Digital SGI-5 (to calibrate speed) was hooked up the installer hooked the power source to the wire that powers the ECM. Could this drain on power from another device damage the ECM.
About ready to install another ECM as everything else check out ok.

Thanks

puzzigully

AJ123,

I have the same issue.

The wire glows, but the ECM still throws the code...

I feel the only way is to see what the ECM sees.
Once I fix the alternator issue, I'll try again this week.

You may be in the same boat?

AJ123

Been working on this for several months. I started this thread an have gotten lots of good advice.
Have my friend John working on this at his shop. He is a great mechanic. I don't feel as stupid after watching him try to clear this up for me.
Good luck. If we get the answer will let you know.
Steve

Cliff Harris

I have been looking at the ECM program code in my spare time...

The ECM waits 5 seconds after ignition-off to start the MAF burnoff. The burnoff lasts 1 second. The ECM shuts down 11.3 seconds after ignition-off. The burnoff test starts 0.3 seconds after burnoff starts. The ECM make 6 voltage measurements and all 6 must be within the voltage window to pass the error code 36 test. On my car that window is 0.4 volts to 1.90 volts.

The oscilloscope waveforms I added to post #52 in this thread show all this...

AJ123

Cliff we may try something new with a different ECU and a different Prom

http://tpiparts.net/ecms_and_proms/


1986-1989 - 1227165 ECM - Camaros, Firebirds, and Corvettes

This is the most common ECM which is used on MAF style setups. ECM number 16198259 is equivalent and can be used in its place without any problems. The same computer was used both for 305 and for 350 engines. The only difference between the two engine sizes was the PROM that was used. The Mass Air Burnoff Module that GM used in 1985 is no longer present. This model is part of the P4 ECM family. This ECM can be easily recognized by having the PROM access cover in the center of the unit, and has only two harness connectors.

Support for this ECM with regards to PROMs is much more common. Due to the nature of the MAF sensor, it is very easy to run a large or moderate cam without needing PROM changes. This system is not very sensitive to engine changes, and can adapt fairly well. However, many enthusiasts find that it is a little more difficult to fine tune than the later Speed Density system. Please realize that this is a matter of opinion and personal preference. Each of these systems have advantages and disadvantages over one another. ALDL data is sent at 8192 baud, much faster than the 1985 ECM. This allows for several sets of data per second.

I just purchased 16198259 Prom from an 89 Vet. It as shown is part of the
P4 ECM family.

It will be shipped tomorrow. Still working on another way.

puzzigully

Steve,

I know how frustrating this is, as you've been working at this a lot longer than me and I'm pretty frustrated!

My thoughts are that I need to go back to square one and find out why the code is being displayed by the ECM.
Cliff (and his oscilloscope) has been invaluable in determining what the ECM is expecting to see and when/why it will display the code.

Once I know what and when the ECM is expecting to see AND I can see what the ECM actually saw, we might have a lead.

I'm not a big fan of swapping out stuff to see if fixes the fault.

I've read many of the Code 36 fault posts and quite a few say they change X and the error goes away, only to come back sometime later.

I'd like to think I/we can put a definitive Code 36 trouble shooting guide together after I solve the problem.
I expect It'd start with the factory troubleshooting guide, but the move onto our experiences.

BTW - I saw a Chevrolet bulletin that claimed a code 36 can be set, caused by a blocked breather tube????
Not sure how that can happen.

AJ123

John the mechanic I have my 87 vet at his shop read some where on this forum that some of the proms in the PC4 family were a partial cause of this code 36 problem sporadic code 36 and ones that would not clear and it may have said that later models of the Pc4 family corrected this problem.

I can not swear that this is correct. We are still trying to find that thread.

AJ123

Does anyone the know the variations in the Prom program from 86 -89 Pc4 family. They all fit the ecm but is the 89 a better program in the prom?

Was wondering if the code 36 was looked at by then. The prom may not be my answer. Just seeking answers to this problem.
Steve

Cliff Harris

In 1989 the cold start injector was eliminated and changes were made to the startup fueling to compensate. The ignition advance is much more aggressive than in earlier years and it is quite common to copy the 1989 timing code into the earlier EPROMs.

The main things to watch for when swapping EPROM programs is the rear axle ratio and manual vs. automatic transmissions. The ECM controls the torque converter lockup on auto transmissions and the shift into overdrive on the 4+3 transmissions. It uses the MPH and RPM to figure out which gear the transmission is in, which is why the axle ratio is important.

AJ123

383 Strocker now and 4+3 has been replaced with a Tom 600
At startup it has been running very clean as we shut off th he 9th injector. Sounds like it should help the lean startup problem. Thanks Cliff
I have an 89 ECM coming and the 89 prom is included.

Cliff Harris

When the engine starts the cold start injector is shut off. It has nothing to do with the way the engine runs (unless it's leaking, of course).

AJ123

Here is another thing that is happening we know that I saw the burn off happen, just the ECM didn't.
When we reset the ecm the vehicle starts up and runs great. If you don't reset it very hard to start and some times with your foot on the pedal for a while before it will idle. Reset code and until we shut it off runs great. Any thoughts.

Steve++

89 ecm and 89 prom is hers

not to the point of trying it yet

AJ123

http://www.ronfrancis.com/prodinfo.asp?number=TP%2D50

TP-50 Chevy TPI Telorvek Fuel Injection Wiring

my last resort

puzzigully

Steve,

Yours sounds almost exactly like mine.

I can see the burn off take place, but the ECM doesn't.

I've fixed the alternator, so will check again this weekend.

I will let you know the outcome of what the ECM actually sees.

puzzigully

I did two tests today..

First was just checking alternator was working etc, but waited until closed loop, then shut down, heard MAF burn off take place, then stopped data collection:


The next was when I realised I hadnt cleared the code 36 before the last one, so I cleared the code, then repeated the test the exact same as above:

Neither of these are showing a burn off voltage being received by the ECM - even though I can see and hear it happening???

It seems as though the ECM is seeing the output from the MAF.

But why isn't it seeing the burn off?

Any ideas?

puzzigully

hmmmmmm

partially answering my own question...

The Fuel Pump relay only stays on approx for 1 sec after the ignition is turned off......

any clues as to what parameter I should be looking at to confirm ECM is actually seeing them and staying on for the required time..

I need to confirm what Cliff said:
The ECM waits 5 seconds after ignition-off to start the MAF burnoff. The burnoff lasts 1 second. The ECM shuts down 11.3 seconds after ignition-off. The burnoff test starts 0.3 seconds after burnoff starts. The ECM make 6 voltage measurements and all 6 must be within the voltage window to pass the error code 36 test.