justonereatta Posted December 31, 2008 Share Posted December 31, 2008 Hello Everyone! I am currently been handed a 1988 Buick Reatta to problem solve that has had been through many hands and many parts. The vehicle will only run in open loop (Cold) when the two wire connector to the alternator is disconnected and A/C Compessor is off. When the connector is unplugged from the alternator and the A/C compressor clutch is not engaged it will run<span style="font-style: italic"> but poorly</span>. Once in closed loop(warm) the vehicle will run with the alternator connected and the A/C clutch engaged??? Another shop claimed to have replaced the Engine Control Module, Body Control Module, Ignition module and Coils, alternator and a battery. It does tend back fire through the intake and fuel foul spark plugs when running poorly? I am out of ideas. Any input on what to do or who to call would make my new year! Thank you for your time...- Justin Link to comment Share on other sites More sharing options...
DAVES89 Posted December 31, 2008 Share Posted December 31, 2008 I would clean the IAC and the EGR. Both how to's are on Ronnies website. Link to comment Share on other sites More sharing options...
padgett Posted December 31, 2008 Share Posted December 31, 2008 With all of that I have to wonder if you have the right PROM. Are the instruments reading correctly ? What is ED99 ?Backfiring and generally cranky/no power are often swapped spark plug wires. Backfires are not good for the MAF sensor.You did not mention if any trouble codes - are there any (can display with any Reatta) ? Link to comment Share on other sites More sharing options...
harry yarnell Posted December 31, 2008 Share Posted December 31, 2008 Don't overlook the possibility of a bad crank sensor. Link to comment Share on other sites More sharing options...
justonereatta Posted January 1, 2009 Author Share Posted January 1, 2009 I did swap out a crank sensor and cam sensor today with no changes. I also cleaned the Idle air control motor and passage along with the EGR valvle and passages throughly. The air gap and reluctor teeth on the crank sensor are all perfect. I inspected the Mass Air Flow Sensor and cleaned it as well with no changes. After speaking with Barney Eaton in Georgetown,Texas this morning I took the plastic conduit of every underhood harness and inspected for opens, shorts and loose conections -none found. I had already performed pin-fit test to every major connector and sensor as well. I did find that the load from the alternator being plugged in and or the A/C compressor clutch engaging appears to just bring a poorly running engine down to a stall. If I remove the engine serpentine drive belt with the accessories all plugged in the will start and run. I even went to the trouble of turn the alternator over with a drill while the belt was off/ engine running and no change was made. I then put the belt back on with the camshaft sensor disconnected and it seemed a little crisper??? Make note - none of the module(s) at this time have any diagnostic troubles codes other than the one s I have set unplugging key components. At the end of my even tonight I was checking to see what spark plugs may have fouled while running it today. I decided to unplug the enjectors just as I have done ten times during this project over the past two weeks of testing and found cylinders number 4 and number 6 not dropping in R.P.M.'s at all? I am excited to test the injector patterns and possibly try a BG injector clean at the fuel rail Friday. I did record again a fuel pressure of 35-45 P.S.I today. The fuel tests this afternoon all passed with an acceptable 10% methanol content. I am also keeping in mind the results of the cm sensor test may be a sloppy timing chain?? Thanks again to all trying to help me get through this. Have a great New Year!!-Justin1988 Buick Reatta Hardtop - Red/ Grey 68,000 miles3800 V6 "C" Link to comment Share on other sites More sharing options...
padgett Posted January 1, 2009 Share Posted January 1, 2009 Shouldn't have timing chain issues at that milage. With 35-40 psi on the fuel rail the regulator and pump are probably good. 4 & 6 are on different coils so maybe an injector issue. Are you sure the plug wires are going to the right cyl ? (4 & 6 would be easy to swap at the plug end, I would try it just to see what happens). Link to comment Share on other sites More sharing options...
justonereatta Posted January 1, 2009 Author Share Posted January 1, 2009 When I disconnect any sparkplug wire at the coils there is no change in R.P.M.! -Justin Link to comment Share on other sites More sharing options...
padgett Posted January 1, 2009 Share Posted January 1, 2009 IAC is adjusting. It is amazing what the computer can adjust for. Still, there should be a momentary drop. Wonder what would happen if you disconnected the IAC while idling (so it is fixed). Link to comment Share on other sites More sharing options...
justonereatta Posted January 1, 2009 Author Share Posted January 1, 2009 I have disconnected the Idle Air control Motor, Mass Air Flow sensor and E.G.R. valve individually with no changes...- Justin Link to comment Share on other sites More sharing options...
padgett Posted January 1, 2009 Share Posted January 1, 2009 Did you disconnect spark plug wires with the IAC disconnected ? Have to do both together for RPM to change noticably. Link to comment Share on other sites More sharing options...
justonereatta Posted January 1, 2009 Author Share Posted January 1, 2009 No I did'nt disconnect the Idle Air Control motor when unplugging the injectors or pulling sparking plug wires. I will to so Friday. Thanks for the input!...- Justin Link to comment Share on other sites More sharing options...
Guest DTerry Posted January 1, 2009 Share Posted January 1, 2009 Are you absolutely positive that the spark plug wires are routed correctly? It was mentioned before, but I can't find any response to the question. Link to comment Share on other sites More sharing options...
Jim Posted January 1, 2009 Share Posted January 1, 2009 I know this is overly simplistic but about 10 years ago my Reatta ran very poorly when it went into closed loop. I tried all sort of things. Looked at the plugs and they looked fine. I know the fellow at the GM dealership garage and we tested lot of different things. We both felt the plugs were OK. I went home and a couple of days later on a whim I put in all new spark plugs and that solved the problem. At the time I was doing a damaged Corsica and some of the plugs were broken in the accident so I put my used Reatta plugs in that car and it ran fine. I discovered when the car went into closed loop, the computer took over and the plugs couldn't fire correctly in the leaner condition. The Corsica computer was not as sophisticated. Link to comment Share on other sites More sharing options...
justonereatta Posted January 1, 2009 Author Share Posted January 1, 2009 I triple checked to make sure the spark plug wires are routed correctly. The sparkplugs, spark plug wires, fuel filter and air filter are very fresh. As a matter of fact I have to swap spark plugs out about once a week due to the fuel fouling issue during testing...- Justin Link to comment Share on other sites More sharing options...
Guest kennyw Posted January 1, 2009 Share Posted January 1, 2009 Then: back to basics:> fuel:> spark:> compression:> If the plugs are gasoline fouling and you are replacing with [NeW] plugs,,,,,,,,,then one of the three above is missing. Lets go back 40 years when the [3] were the only thing you had to deal with......Back then many motors were cranked over without spark for so long that all of the OIL GET WIPPED OFF OF THE CYLINDER WALLS. From that point on changing plugs did nothing even with spark because the motor had no compression.........I have just squirted oil into the cylinders via-the plug hole, turned the motor over 4-5 seconds, replaced the plugs and the motor starts instantly and runs on all cylinders......Not saying this is your problem but you seem to have thrown ever thing else at the problem.............ken Link to comment Share on other sites More sharing options...
2seater Posted January 2, 2009 Share Posted January 2, 2009 What does the ignition timing look like in diagnostics? It sounds like it is running in the limp home mode with fixed timing around 10 degrees or so. The other item is a possible vacuum leak. I left a hose disconnected once and it started and ran, maybe a little elevated rpm, but as soon as it warmed up, it blubbered and coughed. Check the PCV closely as it is buried on the back of the manifold and you may want to look at the EGR for a hung valve. Link to comment Share on other sites More sharing options...
Guest simplyconnected Posted January 3, 2009 Share Posted January 3, 2009 Check your throttle position sensor.Also, timing chain slop can be seen by using a timing light while you vary the throttle. Link to comment Share on other sites More sharing options...
justonereatta Posted January 3, 2009 Author Share Posted January 3, 2009 I checked the injector spray today at each individual injector with a GM "J" tool. They all sprayed good. Number number cylinder injector was a little drippy at times but no biggy. I pulled the PROM out the and it says on it" DELCO ANBM 2541" and "1G812". On the side on it is "68767 8816" Patent Number 4,702,706. So hopefully someone can tell me if it has the right chip in it...-Justin Link to comment Share on other sites More sharing options...
padgett Posted January 3, 2009 Share Posted January 3, 2009 ANBM is the correct original ECM PROM for a 1988 Reatta. Later it was replaced by the ANCX mainly to correct the MPG readout. Link to comment Share on other sites More sharing options...
justonereatta Posted January 6, 2009 Author Share Posted January 6, 2009 I ended up checking the crankshaft sensor gap that the previous shop installed and found it way off. Adjusted that and it runs well. Thank you everyone for your help!!!-Justin Link to comment Share on other sites More sharing options...
DAVES89 Posted January 6, 2009 Share Posted January 6, 2009 I went back and read your posts and on 12/31 you stated that you replaced the crank sensor with no changes... Link to comment Share on other sites More sharing options...
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