1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

car studers under cruising speed

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Old Jul 26, 2007 | 04:48 PM
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From: clarksville tn
car studers under cruising speed

the se engine is running ok but when im driving it the car wants to jerk when im say in third gear doing 3-6k rpms trying to keep it steady at each respective rpm. ive ordered new spark plugs it has new injectors and i'm pretty sure the timing is right might have a slight vacuum leak not sure where just like any fuel injected rotary so ive been told. basically would changing out the spark plugs work? the old one are kind of actually new but i think they are fouled they are all black and nasty looking penicillin turned kind of brownish orange.
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Old Jul 26, 2007 | 05:07 PM
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Wait for the Doc to stop in, or you could look for threads on SE motors in the FAQ section. Make sure you've done your homework before you bug him though...
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Old Jul 26, 2007 | 06:08 PM
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well ive messed with everything to see if the valves were bad the tps they seem to be working so i dont know. that is the only reason i ask
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Old Jul 26, 2007 | 06:27 PM
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Check your cap and rotor for wear. Is your TPS properly adjusted? Does it idle fine?

A stumble or miss could be a few things. Vacuum leak is probably the most common. Of course, then it's fuel and spark.

I would also recommend engine grounds from the firewall to the neg. battery terminal and the engine. This may not be the source of your problem, but I have seen many SE's and FC's run much smoother after proper grounding was given to the sensors and injectors.

Good luck.
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Old Jul 26, 2007 | 09:05 PM
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Carburetor? I say to check your floats, they may be too high.
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Old Jul 26, 2007 | 09:20 PM
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Originally Posted by Jeezus
Carburetor? I say to check your floats, they may be too high.
You goofball,lol. This is fuel injected, a SE.

A brownish color on the plugs is just the chemical that is put in the fuel. If the plug is black then you are running rich.

As XLR8 has stated. Grounds and connections to the injectors and especially the coolant temp sensor at the back of the water pump housing have to be clean and tight. The wrong resistance values will change everything.

Since you have pretty much spliced in wiring and such the best advice I can give you at this point is the following.

Recommend you do a ECU pin test. You need to follow the procedure as outlined in the FSM. Pay close attention to the values associated with the coolant temp sensor and the injectors. Other values may affect this also. This will also point out if there is any ground signal problems also.
There are alot of things to consider and factor in when you do a swap and install a wiring harness also.
More testing that can be done is the fuel volume / pressure testing. AFM testing, etc....
Verify that your connections on the AFM ducting are tight. There is the point where it attaches to the AFM, the connecting spot where the 2 halves of the ducting join, the securing nuts at the T/body and the small hose that attached from the ducting to the Plenum chamber.
Spraying down the intake/injection area while it is running and checking for vacuum leaks is advised also.
This should keep you busy for awhile.
Remember, never rule out the basics such as timing/plugs/wires, and cap and rotor also.
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Old Jul 26, 2007 | 09:22 PM
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Originally Posted by rx7doctor
You goofball,lol. This is fuel injected, a SE.
Its been a long night
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Old Jul 26, 2007 | 10:05 PM
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From: clarksville tn
Originally Posted by rx7doctor



Since you have pretty much spliced in wiring and such the best advice I can give you at this point is the following.
well i got this guy out of San Francisco, California to send me a complete se harness ive checked everything an the harness. actually thats how i got the car to start is the new harness. i about jumped to the moon. but hopefully ill go get a grounding kit this next week and i'll properly ground everything i can find to ground right off the negative terminal to the battery. just to make things easy. i have new plugs so.

the car basically has everything that an se has to run the engine gauges fuel pump connection everything pretty much
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Old Jul 26, 2007 | 10:12 PM
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Originally Posted by bugman1973
well i got this guy out of San Francisco, California to send me a complete se harness ive checked everything an the harness. actually thats how i got the car to start is the new harness. i about jumped to the moon. but hopefully ill go get a grounding kit this next week and i'll properly ground everything i can find to ground right off the negative terminal to the battery. just to make things easy. i have new plugs so.

the car basically has everything that an se has to run the engine gauges fuel pump connection everything pretty much
You don't need to add a grounding kit. What you need to do is verify that the grounds you have are clean and tight. Especially the ones for the ECU.

I still advise you do the pin test.
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Old Jul 27, 2007 | 11:14 AM
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I would also test the BAC solenoid per the FSM. This little sucker can give you all kinds of problems if not working right.

In the FAQ there is a link to GSL-SE idle problems. I learned alot about SE EFI from that thread. It's a good read.
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