HELP EO21C

[Guest imported_keystone]

I have a 1990 Reatta hardtop and I am having problem with a fast idle. In gear about 1000 rpm neutral about 1400 rpm. I have change the TPS, TPS plug and IAC.

Adjusted TPS 5 volts incoming and it reads .4 volt at idle and 4.5 volts at full throtle. Checked grounds and they are good. Was an intermittent problem but now constant. When I disconnect battery and try to clear codes it comes right back.

Can someone please help me?

Thanks

Keystone

[padgett]

E021C means a current TPS reading high (which will cause a high idle). Need to check with a scan tool, may be wiring.

[Guest imported_keystone]

Hi Padgett

It's driving me crazy. I checked wires as much as I could w/o a scan tool. Clean IAC port, checked for intake and vacuum leaks and cleaned throttle plate and screen. All logged codes are code 12, code 21, code E021C, E021H and 6552H. Do these other codes help? I do not have access to a scan tool except at an Autozone. Should I go to AZ and check. They let me do it myself?

Thnaks

Keystone

[padgett]

Is the only way to find out - all except the 6552H which makes no sense to me (Prom ID ?) relate to the TPS. Reatta has a built in scan tool, why not just use that ?

[Guest imported_keystone]

Hi Padgett

Mine is a 1990. Please give details on how to do it.

Thanks

Keystone

More info: forgot to mention: When I diconnect battery to clear codes and then try to start it just cranks. I have to depress the accelerator almost all the way do to get its started. After that initail startup it starts normally except for the fast idle every else is normal. I then check and all the same codes are set as described above. Please help

Thanks

Keystone

[2seater]

How are you getting the codes? You have to have a scanner or be in onboard diagnostics to get that. To enter diagnostics on the '90: key on, press off and temp ^ on the climate control at the same time and hold for a couple of seconds. All the IPC will light up and then release the buttons. The stored codes will read out on the odometer. After it cycles through the codes it will read "Ec ?". Press fan up on the climate control again and it will read "Data Ec?". Press fan up once more and it will show the readings from the various sensors (this can also be done while driving, a very useful tool). To advance to the next reading press fan up, to go back to a previous sensor press fan down. To exit diagnostics, press bi-level or turn the key off. To read the TPS, go to ED01, the first item that will show up. It should read right about .4 volts at idle position and increase smoothly as you press the throttle to the floor. The readings you mentioned are right on where they should be. Is it possible that 6552h is really b552h? That would be normal if the battery has been disconnected and is not a problem.

[Guest imported_keystone]

Hi 2seater

You are right on. The code is b552H as you suggest. The other codes I got using the onboard diagonists. I didn't know about how to go the other features until now. The voltage readings I got were using a voltmeter with key on and jumpers (car not running)going between sensor and plug. I will do some more checking and give you more info. Hope we can solve this.

Thanks again

Keystone

[Songman]

I just figured out the built in code scanner today. Haven't figured out all of the numbers yet but it sure is cool! You turn it on by holding down OFF and TEMP UP on the Electronic Climate Control. There are instructions on reatta.net on how to use it and what the numbers mean.

[2seater]

Once you get good at it you can enter and exit while driving, pretty much by touch (no inattentive driving ). It is a very useful tool. The touchscreen guys have a small advantage in the availability of some readings at all times.

[Guest imported_keystone]

I agree its great. Here are my codes with engine at operating temperature and values for engine off and at idle:

code off idle

ED01 4.74 4.70 TPS

ED04 105 91 TEMP

ED06 .7 4.5 INJECTOR PULSE

ED07 .45 .84 O2 SENSOR

ED08 70 25 SPARK ADVANCE

ED10 12.4 13.7 BATTERY VOLTAGE

ED11 20 1745 RPM

ED12 0 0 SPEED SENSOR

ED16 0 0 SPARK RETARD

ED17 0 2482 KNOCK SIGNAL

ED18 0 0 O2 SENSOR CROSS COUNTS

ED19 128 128 FUEL INTEGRATOR

ED20 128 123 BLOCK LEAN MULTIPLER

ED21 0 10.5 AIR FLOW

ED22 150 74 IAC POSITION

ED23 114 117 MANIFOLD AIR TEMP

ED98 0 0

ED99 8064 8064

BD20 0 0

BD21 107 93 WATER TEMP

BD22 35 34

BD23 35 34

BD24 5 5

DB25 27 27

BD26 56 50

BD27 69 42

BD28 59 40

BD32 27 27

BD40 6.2 6.7

BD42 58 58

BD43 0 0

BD44 93 93

BD50 12.0 13.6

BD51 36 30

BD60 0 0

BD61 0 1825 RPM

BD70 20 20

BD71 19 80

BD98 10 83

BD99 244 244

A few things look strange to me like RPM engine off is 20, idle speed is very high at 1745. TPS reads 4.74.

Please help

Thanks

Keystone

[2seater]

The TPS is way off and it may have odd effects on other things. It looks like it is somehow jammed in the full throttle position or there is a wiring problem. You can remove it and have someone watch the reading while it is operated manually. You can also disconnect it and start the engine to see if the warm idle drops back (the check engine will likely illuminate). MAT temperature looks pretty high, it reads out in degrees C. It looks like the O2 isn't warm enough to get good activity, or it is dead. If the idle is 1700+ rpm, it should get the O2 hot enough that it should show some cross counts? Did you watch the O2 (ED07) for a little while to see if it is constantly changing? It should do so at that engine speed if the engine is warm, and it looks like it was plenty warm.

[Guest imported_keystone]

Hi 2seater

Thanks so much for looking over the readings. I agree about TPS. It is a brand new GM part. I plugged the old one and it does the same thing. May be a wiring problem but I am not sure how to locate it. When I accelerate the TPS voltage goes down form 4.70 volts. I think it should be the opposite ie start low (0.4 volts) and go up. That is very strange. I installed a new pigtail and plug in the harness but problem could be before that.

I followed the code EO21 diagnostics chart in service manual(page 8D1-25). Here are the steps and results: It says as follows: TPS volts over 2.5 (yes), Disconnect sensor volts drop below .2 volts (yes), Probe sensor ground circuit wit 12 volt test light light on (yes), Conclusion faulty connection or sensor. But don't think it is sensor or plug since they are new. Could blue (TPS signal)and gray (5 volt reference) wires be shorted? Would that give result I am seeing. Not sure what to do form here. Very frustrating.

Thanks

Keystone

[padgett]

From the IAC value, the high idle is being commanded by the computer (should be under 40). "When I accelerate the TPS voltage goes down form 4.70 volts. I think it should be the opposite ie start low (0.4 volts) and go up. That is very strange. I installed a new pigtail and plug in the harness " - I hate to ask but is there any chance you wired the pigtail backwards. Out er wires a 5v and ground, center is wiper. If ends were reversed it would do exactly what you describe.

Sometime will explain what putting the links on updide down does to a Muncie four-speed.

[Guest imported_keystone]

Hi Pagdett

No problem about questioning, I more than anyone would like to solve this problem. I cut the harness back the length of the pigtail and soldered black to black, gray to gray and blue to blue. After I was done I checked it out Black is ground and I checked it using a test light to the battery and touched to blach wire and the light comes on and with a voltmeter I get nothing. Gray is the 5 volt source and when I check (key on) with a voltmeter between block ground and gray I get a +5 volt signal. Blue is wiper, voltage between wiper and block in pigtail is 0.044 volts. I had the same issue before I changed the pigtail.

Just cleared codes, plugged in jumpers, turned the key on and guess what everything reads normal: 5 volt gray, blue 0.4 volt at idle position and voltage goes up to about 4.2 WOT. But car will not start. Depress throttle to about 3/4 or 7/8 of WOT and the car starts and run but idles fast and the voltage is back to 4.72 on blue wire (wiper).

Now I am really confused

Please Help

Thanks

Keystone

[2seater]

I hope Padgett can shed some more light on this one, but I do know there are two different TPS modules used on GM cars (in this approximate era) and the ground is in a different location between the two. It's a long shot I know. The other possibility is the ECM has a problem if the voltage readings were taken through diagnostics before starting the car.

[Guest imported_keystone]

Hi 2seater

Thanks for responding. The new TPS is a new GM part 25532800 Japan. The one I removed which I think is original has the following markings: SERA363-1 0321 Japan. The readings I have reported are done both through the onboard system and are also measured using a jumper between the TPS and harness plug.

The confusing part is that once the codes are cleared by disconnecting the battery the voltage at idle reads normally (0.40) but the car will not start. I have to press accelerator almost to floor before it will start and then the voltages are wrong again. Do you think that the ecm goes into some different mode since i have to start it this way? Please padgett or anyone else help?

Thanks

Keystone

[BuickCollector]

GN has a "clear flood mode" when throttle was depressed during cranking. Basically, it turned off the injectors. Not sure about the Reatta.

Check for spark during cranking, check for fuel injector pulsing during cranking, and if the TPS is the same as a GN, check the resistance using an OHM meter when the TPS is disconnected. It should change as the throttle moves.

I also have a high idle/high TPS problem....not as high as yours though. If I turn the key on, wait (usually until the antenna goes up) and then start, things are better. (wierd) I've replaced the TPS and connector before (I think the heat last summer fried it). Haven't done anything this time though. I just live with it, because eventually it'll go down.

[padgett]

I would need to see a complete snapshot of all engine parameters just before you try to start. Also need the pressure on the fuel rail (takes a mechanical gauge). Have seen a bad pressure regulator act this way.

[2seater]

I cannot read the number on the one that is on the engine in the car, but my original engine TPS is the same model, SERA 363-1 with a painted #9425 also Japanese (as is our MAF). Just so we are on the same page, as connected, my TPS has the black connected to the plug at the rear (firewall side), the blue is in the center.

If I remember right, your IAC read something like 150 with the key on, meaning it should be open far enough to get air to start the engine. The Reatta does have a clear flood mode, and if the ECM sees the TPS at full throttle, it will shut off the fuel injectors, likely causing the no start. If your TPS is indeed working backwards, pressing on the throttle will bring the reading down closer to the idle position and it will start. Try starting the car with the TPS disconnected. It should start and run, but throttle response may be lousy. This is a very curious situation and if the TPS works as you indicate, the ECM will be very confused and is maybe why the O2 and such is stationary, it thinks it is at full throttle which locks the Integrator and BLM.

[Guest imported_keystone]

Hi 2seater

Sorry for the delay in responding. I have been very busy with work the last few days. Just looked and my plug has the gray wire near the firewall in the plug, blue in the center and black near the front. Do you think mine are wrong? I will tear apart the harness and check my connections. My manual says gray is 5 volt anf black is gound and that is what my volt meter reads. I will try to clear codes and start with TPS unplugged. Also padgett I am trying to borrow a fuel pressure gage. I will post the results when I get them.

Keystone

[Guest imported_keystone]

Hi 2seater

I unplugged the TPS, cleared codes with onboard system. Car starter right up and had good throttle response, idle about 1200 rpm cold. ED01 read 0.04 volts

Keystone

[Guest imported_keystone]

GOT IT !!!

Thanks 2seater and padgett. You asked the right questions long enough and eventually you solve the problem. I ripped apart my wiring harness and just as I remember gray to gray, blue to blue and black to black. Then I looked in my manual again this time to 6E3-A-4 to ECM hookups where it told me gray is 5 volt reference, blue is TPS signal and black is ground just as I have been measuring. However it also says gray to terminal A in weatherpack plug and black goes to C. When I looked at the new Standard Products S564 pigtail I bought and installed it is just the opposite i.e. gray to C and black to A. Used my terminal removal tool and switched the black to C and gray to A, plugged it in , cleared codes and Eureka it works. Who would have thought? Any way Thanks again 2seater and padgett for you help and persistence. This forum is great

Keystone

PS I will have to check Standard Products to see if they sold me the wrong pigtail or if someone manufactured this one wrong.

[2seater]

Likely the wrong pigtail, but it doesn't matter now. For whatever reason, GM used two different pin locations for similar MAF hookups, and I suspect you ran into bad information in the parts guys computer. I am very glad it is now fixed. After a bit of driving, everything else should settle down and the other readings will be happy too