Forum

[Rossrr4]

I have a 2011 C5 that started popping through the intake and resulted in a loss of power around 30mph. I brought it to a shop and the fix was to replace the throttle body and sensors, which worked for around 100 miles, not its back to same problem. I have a K&N air filter installed, and am looking for some advice/help...Cheers

[Presto]

If the replacement throttle body and sensor fixed the problem before then it might seem that the same repair is needed again for the same problem – although I’m a bit surprised that it required a new throttle body – not a cheap item! Maybe a return to the same shop is needed.

[Rossrr4]

I was hoping not. I'm currently in Germany and don't want to have to go through that again. I think it ran about 350 euro and wasn't sure if anyone else had the same problem and if I was going invest that much again, I was hoping a remap or carb conversion would do the trick (although the latter requires a bit more work)

[Rattlebattle]

It seems to me that you should take it back to the shop that "fixed" it. Aside from that you haven't given us much to work on. Mileage? Any other mods e.g. exhaust? Was the EFI adjusted in any way to compensate for the K&N? Which sensors were replaced? (I would expect the tps but who knows?) Is the shop an authorised RE agent? As Presto says, the tb replacement seems extreme unless someone has fiddled with the "throttle stop". Is it just 30mph it plays up? In top gear only?

[Rossrr4]

It has 4300 miles, and did have an aftermarket exhaust on it at one point for around 200 miles. I took it off and put a K&N air filter on it. The EFi has not been "adjusted" as far as I know and should have the original map on it. The shop it an authorized RE shop and he tested tps, o2 and 1 other sensor and all check out. He took a throttle body off a new bike, put it on mine and it worked fine. He could not explain why it made the difference, but it did. He rode it for 40 miles or so and I did another 60. It started acting up, so I put it up (he was swamped with work, and I was out of the country for a few months). Now here it is the spring and I'm looking to see if anyone else had the same problems. It gives up power around 30, no matter the gear, although you can fiddle with the throttle to keep it going to a good place to stop, but the popping gets more and more and gets pretty bad (blowing the filter door open). I don't have the original filter as it was misplaced in the more, but didn't think that the filter alone would cause that much of an issue.

[Rattlebattle]

When the tps connection was loose on my C5 it ran gradually worse and worse until it wouldn't run at all. The MIL would light intermittently in the early stages but eventually stayed on permanently. I assume you MIL remains unlit after the initial self-test? If it does come on after then you can read the stored fault codes by grounding the ECU using the spare lead attached to it for that purpose, turning on the ignition - don't start the motor - and counting the number of short and long flashes. There will be more than one sequence if more than one fault is stored. The first is the latest. Try the simple stuff first: Has the spark plug been changed recently. I'd it a good colour and the proper grade? Is the plug cap to plug connection sound? The originals often had poor connections. Are the sensor connections all sound, particularly the tps? Are the battery terminal connections tight? On the C 5 the wires are too tight, causing breakage of the connectors and the little wire connected to the negative terminal. I have to say that I got totally fed up with a succession of weird and mostly intermittent faults on my C5, so when H introduced a cheaper version of their carb conversion I bought one and haven't had any issues since. It's a cheaper option than a PCV, which works well but only on a sound EFI system. BTW I'm not sure about fitting a K&N without a remap via PCV. If it flows more air the ECU will compensate by richening the mixture....

[Jack the Lad]

Hi rossrr. I would start with investigating cheap and simple things. In my experience over the last 25,000 miles nearly every problem is electrical and relatively easy to fix. Have you checked that the battery is in good nick, that the reg/rect is working and that the charging and ignition circuits are in good order. On mine popping and loss of power was a sign that the reg/rect was on the blink. Eventually the battery died, but it took a few hundred miles from the first symptoms before death. Hope that helps.

[ric]

Definitely worth checking the Sensor connections. Ensure the tangs on the metal spade connectors are all fully engaged inside the connector blocks themselves.
Visually checking that the two halves of the connection block are locked together by the external plastic tang on these bikes does not guarantee a good connection.