Code 45 1988 TPI Engine skips while cruising
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Joined: Aug 2009
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Code 45 1988 TPI Engine skips while cruising
Hi,
I'm new here. Hope someone can help. Have 1988 Corvette, getting code 45. Motor skips and loses power while driving at a constant speed. Have replaced the following with new parts; Not sure what to do next.
Plugs
Cap and Rotor
Fuel Filter
EGR Valve
PCV Valve
O2 Sensor
Plug Wires
Thanks
Chris
I'm new here. Hope someone can help. Have 1988 Corvette, getting code 45. Motor skips and loses power while driving at a constant speed. Have replaced the following with new parts; Not sure what to do next.
Plugs
Cap and Rotor
Fuel Filter
EGR Valve
PCV Valve
O2 Sensor
Plug Wires
Thanks
Chris
Instructor
Joined: Apr 2009
Posts: 115
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From: Rising Sun Md.
My 87 has a intermittent check engine at cruise that is on for a minute at a time and comes on about 3 times an hour...I need to get a code reader but will not waste the time until I do a full tune
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I disconnected the cold start valve connector. I measured 3.9 ohms across the valve connector. I measured the DC resistance of all the fuel injectors, they were all approximately 16.8 ohms. I took the car for a drive with the cold start valve disconnected, and as soon as the water temp got up to about 135 degrees, the engine started skipping, and service engine light came on after about 5 minutes (code 45 again). I took the car back home and put it in park. The idle would drop down to 400, 500 RPMs for a few seconds, and then go back up to 700, 800 RPMS, and then repeat. Also I disconnected the vacuum hose from the pressure regulator, and there was not any fuel in it.
Any suggestions on what to do next would be greatly appreciated.
Any suggestions on what to do next would be greatly appreciated.
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Joined: Jan 2006
Posts: 77
Likes: 1
1988_Chris,
I'm in the same boat as you:
http://forums.corvetteforum.com/c4-t...regulator.html
First thing....go to the auto parts store and get a fuel pressure gauge and hook it to the Schrader valve on the fuel rail to see if it is holding pressure when the engine is turned off. If not, pinch the fuel return line, cycle the fuel pump to create pressure and see if the pressure still goes down (like mine is doing).
Right now, on my car, everything is pointing to fuel injectors.
How old are your injectors, FPR?
I'm in the same boat as you:
http://forums.corvetteforum.com/c4-t...regulator.html
First thing....go to the auto parts store and get a fuel pressure gauge and hook it to the Schrader valve on the fuel rail to see if it is holding pressure when the engine is turned off. If not, pinch the fuel return line, cycle the fuel pump to create pressure and see if the pressure still goes down (like mine is doing).
Right now, on my car, everything is pointing to fuel injectors.
How old are your injectors, FPR?
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Thread Starter
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My injectors are the factory originals. I'll get a fuel pressure gauge tomorrow and see where I'm at. Does the fact that the motor starts skipping after it warms up give any indication of what's happening?
Thanks for the info.
Thanks for the info.
Instructor
Joined: Feb 2008
Posts: 177
Likes: 5
From: Toronto Ontario
The skip you mention can happen when the car goes into closed loop as it warms and the integrator (short term fuel trim) is trying to lean out the mixture because of a rich condition as indicated by Code 45. It reaches it's limits and then resets which can cause a stumble. You can notice this at idle as well...the engine will lope. This is often caused by faulty injectors... make sure to measure the resistance when hot.
Last edited by gmboileau; Aug 5, 2009 at 10:45 PM.
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tested fuel pressure
I'm still struggling with this code 45 problem.
Just tested fuel pressure, results as follows
Engine off key on - Steady 39 PSI
Engine off key off - 38 PSI slowly drops to 35 PSI after 10 or 15 minutes.
Engine on Idling - 36 PSI until car warms up
Engine on Engine Warmed up - As idle drops to 400 RPM pressure rises to 41 PSI then engine goes back to normal 700 RPM, pressure then drops back to 36 PSI - Then repeats as engine goes from 700 to 400 etc.
I tested DC resistance of all of the fuel injectors while the engine was warm, here are the results. 17.3, 17.5, 17.4, 17.5, 17.4, 17.3, 17.3, 17.2.
I'm not sure what to do next. Some other posts have indicated that this may be a fuel injector problem. I'm not sure though. Any help here would be greatly appreciated.
Just tested fuel pressure, results as follows
Engine off key on - Steady 39 PSI
Engine off key off - 38 PSI slowly drops to 35 PSI after 10 or 15 minutes.
Engine on Idling - 36 PSI until car warms up
Engine on Engine Warmed up - As idle drops to 400 RPM pressure rises to 41 PSI then engine goes back to normal 700 RPM, pressure then drops back to 36 PSI - Then repeats as engine goes from 700 to 400 etc.
I tested DC resistance of all of the fuel injectors while the engine was warm, here are the results. 17.3, 17.5, 17.4, 17.5, 17.4, 17.3, 17.3, 17.2.
I'm not sure what to do next. Some other posts have indicated that this may be a fuel injector problem. I'm not sure though. Any help here would be greatly appreciated.
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Joined: Jan 2006
Posts: 77
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Chirs,
I just fixed my problem (re-set base idle and replaced fuel pump helped the most). I would suggest re-setting the base idle on yours as well (might not fix the root issue, but may help).
From Vader's page:
http://temp.corvetteforum.net/c4/vader86/baseidle.html
I just fixed my problem (re-set base idle and replaced fuel pump helped the most). I would suggest re-setting the base idle on yours as well (might not fix the root issue, but may help).
From Vader's page:
http://temp.corvetteforum.net/c4/vader86/baseidle.html
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Joined: Jan 2003
Posts: 20,301
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From: Summerland B.C. Canada
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Situation Much Worse
Disconnected MAF connector last week troubleshooting. Car ran horrible. Reconnected MAF, car ran much better. Next thing I know I get an O2 sensor code, egr code, plus rich exhuast code. Completely disgusted.
My next step is to get a real shop manual for my 88 vette.
Can someone please provide a link so I can purchase the real manual? I'm currently using a Chiltons manual, which is a little disapointing.
Thanks
Chris
My next step is to get a real shop manual for my 88 vette.
Can someone please provide a link so I can purchase the real manual? I'm currently using a Chiltons manual, which is a little disapointing.
Thanks
Chris
Team Owner
Joined: Jan 2003
Posts: 20,301
Likes: 240
From: Summerland B.C. Canada
Here is some info from my 86, should provide help until you get your own manual. http://members.shaw.ca/corvette86/
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Finally Fixed
Used Agent 86's pdf repair sheets to troubleshoot code 13, 32 and 45 over the last month or so. All of the codes would come and go. Very frustrating. The test that led me to the fault was "shorting diagnostic terminal to ground", Run engine at 1200 to 1800 RPMs and watch for service engine light soon to stay on. Then ground o2 sensor and start engine. If light is steady ECM is bad. Puchased ECM from Ecklers $180.00. Just put it in tonight and vette runs like a champ.
Thank You to everyone who helped with this frustrating problem, especially Agent 86.
Chris
Thank You to everyone who helped with this frustrating problem, especially Agent 86.
Chris
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Joined: Jun 2009
Posts: 95
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From: Rochester NY
Great to hear - I'm looking at a very similar issue on my 91. I don't see the loss of power at speed but once I've been driving for 45 minutes or so on a warm day, she really has trouble idling. Up and down, up and down. It mostly disappeared after chucking the frisbee so I didn't worry about it much. Checked the codes a few days ago and I saw 45. I already checked the injectors a few months ago (only while cold, however) and they range from about 10 to 16. Since then I've been waiting on a new set (multecs, but they're new and free) but I think this weekend I might give the ecm check a try.
Thanks for posting your solution!
Thanks for posting your solution!
