Researched acceleration issue, but unsure of next steps - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


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Old 09-12-2005, 05:30 PM   #1
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Default Researched acceleration issue, but unsure of next steps

I've been researching this problem by searching thru old posts, but I thought I'd run it by all of you.

Overall, my '93 SSE has very flat acceleration and lackluster throttle response. Occasionally it will backfire if I try to accelerate quickly enough to cause a downshift and the acceleration is delayed. There is no problem or interruption with power once I get to cruising speed.

In addition I have an issue where after a cold start (which would start normally), the engine is very tentative for the first couple hundred yards. Any attempt to accelerate makes me feel like the engine will kill, but it never does. Suddenly, it clears up and the driveability is then like the first paragraph above. This cold start thing does not happen consistently like the first condition, and often the amount of degradation varies, too. The check engine dash light never comes on during any of this.

I replaced the plugs and cables yesterday, and that seemed to help the cold start thing somewhat, although it may take another day to be sure. The old plugs looked pretty normal, but the cables were definitely bad. One boot easily separated from the cable when we took it off the plug, another boot was corroded inside. I got it to backfire only once immediately after we changed the plugs and cables and that was while in park and hitting throttle quickly, but not revving it hard.

From what I've read on the site, next steps might be coil packs, O2 sensor, or ??? Or is it better to try to get diagnostic codes first? I had the injectors cleaned in '99, and I have the air filter changed regularly. Otherwise, nothing else has been done.

This sounds like a lot of the other posts I've read, but I'm not sure what to try next. Thanks in advance!
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Old 09-12-2005, 05:33 PM   #2
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Pull codes before spending any more money. Use the procedure in Techinfo. If no codes, get a scantool and check for history codes, then do a 'live' scan while you drive. I'm suspecting a bad crank sensor off the bat, and they don't ALWAYS set an SES light.
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Old 09-12-2005, 05:35 PM   #3
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hrmmmm.... perhaps a fuel issue? have you checked your fuel pressure lately?
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Old 09-12-2005, 06:27 PM   #4
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The backfire issue tends to point the opposite direction. From fuel to timing.
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Old 01-23-2006, 11:30 AM   #5
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Default Researched acceleration issue, but unsure of next steps

Hello again!

This is a continuation of my original post last Fall. I have progressed (slowly) since then with the issue. My original description of very poor engine response in the first minute of running the car ('93 SSE) is at the top of this thread. Also acceleration seems flat once the engine IS running smoothly thereafter. Nothing has changed. I had replaced the spark cables as a first step with no improvement (but they WERE old). However since then, I have the followed the standard advice: tried pulling engine codes using the "trick" under-dash method and received no indications of problems. I also replaced the fuel filter (no improvement) and finally checked the fuel rail pressure. I read 40 PSI at ignition switch-on, which dropped to a fairly steady 34 PSI with engine running. Definitely under-spec according to the info on this site. But I also tried driving a bit with the fuel gauge in place and noticed that when the engine was having its normal fits in the first minute (severe hesitation, sputtering, etc.) that the pressure stayed pretty constant at 34 -30 PSI. I would have expected more deviation. Is this typical of a weak fuel pump or is there something else, too?

Thanks!
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Old 01-23-2006, 12:04 PM   #6
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I have an Actron CP9145 scanner. It is not the best scanner, but if it will help and provide the data you need, you are welcome to borrow it. I don't have the OBDI cable, but we can get one.
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Old 01-23-2006, 01:24 PM   #7
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Quote:
Originally Posted by Echo SSEI
I have an Actron CP9145 scanner. It is not the best scanner, but if it will help and provide the data you need, you are welcome to borrow it. I don't have the OBDI cable, but we can get one.
Thanks! I might just do that! I assume I can contact you via private message, but I may not get to it until later this week. But stay please tuned!
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Old 01-23-2006, 01:45 PM   #8
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Quote:
Originally Posted by kicksock
Quote:
Originally Posted by Echo SSEI
I have an Actron CP9145 scanner. It is not the best scanner, but if it will help and provide the data you need, you are welcome to borrow it. I don't have the OBDI cable, but we can get one.
Thanks! I might just do that! I assume I can contact you via private message, but I may not get to it until later this week. But stay please tuned!
No Problem...might save you the hassle of buying a scanner. PM works fine....I am on EVERY day
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